Coil pack replacement

Got code for cylinder five misfire, so replaced plug didn't help. Move on to what I have always called a coil pack. But that's not what it comes up on as being called on any parts website. The part my local parts store gave me is exactly or similar to ones I c online bit not same as one I pulled out. My question is, the mounting base plate different on aftermarket replacement. It is smaller in size will this affect operation of it.