This is all very easy to look up on the net. Try and find the US Sniper manual. Has great info in it on concealment and lots of other stuff.
Crawl suit:
Pros:
- Lightwieght (compared to full ghillie).
- Able to crawl in, low profile.
- Easy belt acces.
Cons:
- When standing up, less concealment when viewed frontal.
- Less concealment when kneeling.
Full Ghillie suit:
Pros:
- More concealment when standing up straight.
- More concealment when kneeling.
- Less chance to be noticed when viewed frontal.
Cons:
- Heavy(compared to crawlsuit).
- More bulky, can be hard to conceal that much fluffy jute and what not.(this may not be true but it is how I see a full suit.)
- No easy belt acces.
- Not able to crawl in, thus harder to move unseen.
- Needs vegetation on the front, which might be in the way when bending over.
There's probably a lot more, but this is what I could think of atm.