why is this?

[miniTIGER95]

I bought a nike SQ driver about a year ago, and haven't been able to hit it consistantly at all, no matter how much time at the range, its always slices about 35 yards no matter how well i hit it. I hit my other clubs fine with a natural ball flight of around a 5 yard fade.
I went back to my first callaway big bertha driver which is about 10 years old and im loving it, so much better results but why??

 

[GreiginFife]

Probably a multitude of differing characteristics between the two to define exactly why. Shaft length, shaft flex, head size, head dynamic, CoR, grip type/size... the list is huge. Then there are other factors like confidence, how you feel looking down at the club at address, for me it has a bearing on how you hit.