Difference between Blade Pro V8 - V7

what is channel? Im talking about feeling comparison

Inside the handle there are two channels that run the length of the pallet/hairpin. Usually these are hollow, but some companies add foam or silicone. Silicone dampens the vibrations (some would say "feel") the most. My V7 came with foam in both channels, and one of my V8's came with foam and silicone. My other V8 is both foam.

The V7 and V8 are supposed to be the same exact racquet with a different paintjob, but some report lower swing weights on the V8. This is likely to do with quality control from Wilson. A higher swing weight is going to feel heavier/harder to swing, but will feel more solid on contact.

You should visit the Official Blade Pro thread to see a more in depth discussion on people's experiences with their V7's vs V8's.