The short answer is, "it depends". Packs sold to women may have only superficial changes compared to the men's version (i.e. the color is different), but there are usually a few common differences:
- Shorter torso length (distance from shoulder to hip, often shorter in women).
- Narrower shoulder straps (men tend to have broader shoulders).
- Shape of shoulder straps (sometimes you'll see S-curved straps to fit better around breasts).
- Size and shape of the hip belt.
Except for item 3, which is less common, these differences aren't inherently female-specific. It's not uncommon for women to use men's packs and vice versa. The best recommendation is to try the pack on and see how it fits. An incorrect torso length will probably stand out the most, but be cautious of how well the hip and shoulder straps fit. For extended trekking purposes, it's worth loading your pack with its expected weight and spending a good amount of time (at least 15-30 minutes) walking around with it on.
Finally, if the larger pack doesn't end up fitting, all is not lost; there are ways to do longer treks with smaller packs if you have the time to make some changes to your packing list.