Let me try and break it down for you!
Face & Body is a MAC store exclusive, and is a beautiful foundation that can be used on, guess what? The face and body! It has a gentle metallic-dewy finish that is very pretty. It has a really low coverage so it's more of a tint for the skin. Adds a healthy glow to skin. I love it on normal or a little drier skin because it really adds a soft moistness to the skin if that makes any sense. Makes it look healthy. NOT for oily skins. You can definitely wear it if you have oily skin, but it can tend to look oily or wet if you get really oily throughout the day.
Hyper Real SPF 15 is similar to Face & Body, but available at all MAC locations. It has a more noticable pearlescent glowy finish than F&B, but it has a similar coverage. It also contains SPF. It's a little more flashy and glowy than the other one, but it looks gorgeous on drier skins as well. NOT for oily skins.
Studio Fix Fluid SPF 15 is a liquid with a medium-full coverage and is buildable. It is great for any skintype, though I prefer it on more oily skins because it helps balance it out since it's a natural matte finish. It contains SPF 15. I especially love this for break outs. It's very gentle and does not feel heavy at all, but gives a great coverage that will make anyone breaking out a flawless face. What I wear everyday.
Select SPF 15 is similar to Studio Fix Fluid SPF 15. They both share a natural-matte finish, as well as SPF protection. Where they differ most importantly, though, is the coverage. Whereas Fix is more of a full coverage makeup, Select is a lowmedium to medium coverage. It is, however, buildable, so if you don't need alot of coverage, but frequently need a little more coverage in a few places, it is achievable by putting a few light layers as necessary in some places. Very lovely on dry and oily skins since it is a little more moisturizing than Fix, but has a beautiful matte finish.
I hope that helped!!