Both essentially look the same because the leg press looks like reclining squat but I have to say that they are quite different. You can say that they’re like brothers but with rather different personalities. Kind of like Charlie Sheen and Emilio Estevez.
1) Compound exercise – multi-jointed movement: hips and knees
2) Predominantly works the glutes, quads and the hamstrings (to a smaller extent the calves)
1) Leg press has a shorter range than full range squats
2) Squats requires more stabilizing muscles
The big question is this: What are your goals and what are your limitations?
Back problems* – Neither. I would go for isolation or isometric exercises like extensions, curls and wall sits.
Hip problems*- Leg presses or box squats
*check first with your physician if it’s serious
Growing your legs (hypertrophy) – Squats AND leg presses and in that order
Jennifer Lopez booty and legs – Squats
Strength – Squats but if you’re trying to get stronger for deadlifts then leg presses (angle mimics the bottom range of deadlifting)
Sports – Depending on what sport you’re playing but most would benefit more from squats. Rowers would do well with leg presses (mimics it)
To impress the girls – Leg presses simply because you can rack it up especially if you’re short like me
Both exercises are pretty awesome but learn proper form and choose wisely depending on your goals and limitations. Most newbies and girls tend to gravitate towards the leg press because they’re unsure. So here’s a great link to learn proper squat form so you don’t look like these gym fails.