Mostly it's just semantics. Think of it in terms of facial moisturizers. There's lotions creams gels etc. They are all mositurizers just of different viscosities. So whether it says butter - lotion - oil etc. They do similar things.

What makes the difference is the "type" of product. Curl enhancers are designed to maximize the amount of curl to your hair. Gels are designed to provide definition and hold. Leave ins are designed to provide additional moisture.

A leave in spray and a leave in cream are designed to do the same thing. Impart mositurization. Gels and mousses are designed to do the same thing. Provide hold. Pommades - pastes - etc are designed to help provide definition (and some hold). It's very confusing so it's not a stupid question at all.
CG - 3/27/09
3b - dry - medium texture/medium porosity!
Co wash/rinseout/leave in: currently auditioning products
Styling: lube and BRHG