I'm unsure of the proper terminology, but the standard paperback book is about 4" wide and almost 7" tall. Lately, some of the better-selling books have been coming out in a taller format, still only about 4" wide but now 7 1/2" tall. I suppose it's to make them stand out more or something, but it irritates me, especially when I have a series that started out in standard paperback format (like the "Agent Pendergast" series by Douglas Preston and Lincoln Child) that now comes out first in hardback and then in the "tall" paperback format. So much for standardization on my bookshelf!
There's also an even larger format, about 5 1/4" wide and 8" tall, that's comparable to a hardback book but comes in paperback format. Is that the trade paperback size you referred to?