These two console plugins are modeled from two completely different analog desks, so their inherent sound is quite different, along with the features they offer. While both are channel strips meant to make the incoming audio sound better, the quality of their processing is quite different.
Please google Neve desks (bx_console N) and SSL desks (bx_console SSL E) to read more about how the two differ from each other. It could be said that the bx_console N provides a warm and saturated sound, while the SSL plugins have a bit more aggressive and punchy sound. This, of course, is a matter of opinion, and each plugin is equally capable of delivering warmth, punch, and aggressive character to your tracks.