The ingredients really are virtually identical. All three conditioners have the same ingredients and they virtually follow the same order. The only change is the position of bisaminopropyl dimethicone and cetyl alcohol in smooth and soft. However, I would not read too much into it as  in truth if you have the same amount of cetyl alcohol and bis-aminopropyl dimethicone you can list either one first.

The real test is in using the product and for me there are clear and distinct difference

Smooth and Soft - I used to think hello hydration was awesome until I met this guy. This is an all singing, all dancing conditioner with incredible softness. It has quite a strong scent but the softness it gives makes it worth bearing.

Hello Hydration - The one I used to love. It does give hair a wonderful softness but it has been trumped by smooth and soft.

Tousle Me Softly -  Nothing bad but nothing to write home about either. I only bought it because I have a herbal essences fetish...if they make something I will try it (except for straight hair/shine). I have also tried beautiful ends (in a red jar marketed for split ends) and the result is similar - nothing to write home about.

There are subtle differences in these products that you cannot tell by looking at the ingredients. The difference may be as little as 0.5 to 1% more of a particular ingredient which does not necessarily change its position in a list but radically alters the feel of the product.

I would always recommend that you read the product claims. Clearly the conditioner for naturally wavy hair or for hair with split ends is not for me as my hair is not naturally wavy and it does not really have split ends. The conditioner that works best for me is one for dry and frizzy hair (I do not describe my hair as frizzy but I would think that when the average joe describes frizz, my natural curl pattern would fall into that definition at the extreme end.)