I think what makes them appear to have similar styles is their bodies.
Both tall, lanky, no visable muscle with a big arm reach.

But while Pavlik shoots his power straight right hands and hooks (For the most part upstairs). Jr concentrates more on the body attack with hooks right and left downstairs. Just recently Jr. started using his straight right in his last 2 fights as he is developing it more. Hes starting to realize he can hurt his opponents with that right hand and is throwing it more mixing it upstairs and downstairs shots.