Assuming you already know all the different kinds of Winbond ICs and their charateristics, with UTT added means they're untested and are made with newer manufacturing process.
Note that CH-5 UTT matches the charateristics of BH-5 and BH-5 UTT. For some reason it doesn't act like the original CH-5 at all.
I suppose I could give you a run down of EVERY single Winbond's DDR1 ICs but that'll take ages.