I'm not sure but to me, it seems that the purpose of both products are different. A conditioner is designed - generally speaking - to moisturise and detangle your hair. A cream can be moisturising, but belongs to the category of styling products.
However, I must admit that I don't have any sources for this other than my own experiences.
F - LP - HD - NE
Fine, low porosity, high density, normal elasticity
Low poo: Burt's Bees Very Volumizing Pomegranate Shampoo
Protein: IAGirl's gelatine treatment
Detangler & LI: KCKT
Beauty Is Not a Number