Please be aware that even a trip that was labelled as not very strenuous can become strenuous or very strenuous with changing snow and or weather conditions. 

Not Very Strenuous: Up to 2000 feet of vertical gain; 8 kilometers  (5 miles) of distance
Moderately Strenuous: 2500 to 3500 feet of vertical gain; 12 kilometers (about 7.5 miles) of distance
Strenuous: 3500 to 4500 feet of vertical gain with a day pack for several days in a row.
Very Strenuous: 3500 to 4500 feet of vertical gain with an overnight pack for several days in a row or more than 4000 feet with a day pack at higher altitude for several days in a row.
Extremely Strenuous: More than 5000 feet of vertical with an overnight pack for several days in a row

Low: requires basic ski touring equipment and skills. No prior ski touring experience is required.
Moderate: involves technical skinning or easy booting, such a skinning with ski crampons and or booting up a 40 degree snow slope. Basic knowledge of kickturns are expected.
High: requires complex transitions and easy glacier travel; involves some third-class sections of climbing with crampons. Strong technical skinning skills in difficult and potentially exposed terrain.
Very high: makes a strong transition into ski mountaineering that may require the use of an ice ax and crampons; involves some fourth-class sections, rappels, and moderate glacier travel, prior experience of skinning in technical terrain is an absolute must.

Easy: No prior rock climbing experience required
Moderate: Rock climbing to 5.7 difficulty
Difficult: Rock climbing to 5.9 difficulty or lower is the climb is longer multi-pitch climb
Very difficult: Rock climbing to 5.10 difficulty and above or for very long trad routes of moderate difficulty (5.9)

Not very strenuous: up to 1000 feet of vertical gain for the approach and only a few pitches of climbing
Moderately strenuous: 2000 to 3000 feet of vertical gain for the approach followed by multiple pitches of climbing
Strenuous: more than 3000 feet of vertical gain for the approach, followed by a multi-pitch route
Very strenuous: more than 3000 feet of vertical gain for the approach, followed by a long multi-pitch route involving sustained climbing difficulty

Low: requires no prior rock climbing experience
Moderate: some prior rock climbing experience along with knowledge of tying in and belaying.
High: solid rock climbing experience, along with tying in, belaying, and anchor building skills in a sport climbing setting
Very high: solid rock climbing experience, along with tying in, belaying, gear placement, and anchor building skills in a traditional climbing setting

Easy: No prior rock climbing, glacier travel or ice climbing experience required.
Moderate: Rock climbing in exposed 4th class or easy fifth class terrain in mountaineering boots, glacier travel in crevassed terrain.
Difficult: Rock climbing in exposed 4th class up to mid fifth class terrain in mountaineering boots. The route could involve substantial time on the front points of the crampons with some moderately steep ice climbing. Some of the movement can be on rock with crampons on in exposed terrain. Some previous ice climbing experience recommended.
Very difficult: Rock climbing in exposed 4th class up to 5.8 class terrain in mountaineering boots. The route could involve substantial time on the front points of the crampons with some steep ice climbing. Some of the movement can be on rock with crampons on in exposed terrain. Prior ice climbing experience needed.

Moderately strenuous: 2500 to 3500 feet of vertical gain with a one day alpine climbing pack
Strenuous: up to 3500 feet of vertical gain with a one day or overnight alpine climbing pack Very strenuous: 3500 feet or more of vertical gain with a one day or overnight alpine climbing pack
Extremely strenuous: 5000 feet or more of vertical gain with a one day or overnight alpine climbing pack

Low: requires no prior rock climbing, glacier travel or ice climbing experience
Moderate: some prior rock climbing and or glacier travel experience along with knowledge of tying in and belaying
High: solid rock climbing experience, ice climbing and glacier travel experience, as well as experience with camping in a remote setting
Very high: solid rock climbing experience, along with tying in, belaying, gear placement and anchor building skills in a traditional climbing setting

There are several systems in current use to grade mountain climbs. Alpine mountaineering routes are usually graded based on all of their different aspects, as they can be very diverse. Thus, a mountain route may be graded 5.6 (rock difficulty), A2 (aid difficulty), WI3 (ice climbing difficulty), M5 * (mixed climbing difficulty), 70 degrees (steepness), 4000 ft (length), VI (commitment level), and many other factors.

In contrast to the French numerical system (described earlier), the French adjectival alpine system evaluates the overall difficulty of a route, taking into consideration the length, difficulty, exposure and commitment-level of the route (i.e., how hard it may be to retreat). The overall grade combines altitude; length and difficulty of approach and descent; number of difficult pitches and how sustained they are; exposure; and quality of rock, snow and ice. These are, in increasing order:[19]

F: facile (easy). Straightforward, possibly a glacial approach, snow and ice will often be at an easy angle.
PD: peu difficile (slightly difficult). Routes may be longer at altitude, with snow and ice slopes up to 45 degrees. Glaciers are more complex, scrambling is harder, climbing may require some belaying, descent may involve rappelling. More objective hazards.
AD: assez difficile (fairly difficult). Fairly hard, snow and ice at an angle of 45-65 degrees, rock climbing up to UIAA grade III, but not sustained, belayed climbing in addition to a large amount of exposed but easier terrain. Significant objective hazard.
D: difficile (difficult). Hard, more serious with rock climbing at IV and V, snow and ice slopes at 50-70 degrees. Routes may be long and sustained or harder but shorter. Serious objective hazards.
TD: très difficile (very difficult). Very hard, routes at this grades are serious undertakings with high level of objective danger. Sustained snow and ice at an angle of 65-80 degrees, rock climbing at grade V and VI with possible aid, very long sections of hard climbing.
ED1/2/3/4: extrêmement difficile (extremely difficult). Extremely hard, exceptional objective danger, vertical ice slopes and rock climbing up to VI to VIII, with possible aid pitches.
ABO: Abominablement difficile (abominable) Difficulty and danger at their limit.
Often a + (pronounced Sup for supérieur) or a − (pronounced Inf for inférieur) is placed after the grade to indicate if a particular climb is at the lower or upper end of that grade (e.g., a climb slightly harder than "PD+" might be "AD−").