I have separated protein sequences of a particular family into two groups (according to some property). I will like to identify motifs that are present in the first group but absent from the second group (if there are any).

I understand that I can use MEME in discriminative mode or differential enrichment mode. But, it appears that doing this identifies motifs that are enriched or more abundant in the first set relative to the second. And this is not what I want.

Is there a way to identify motifs that are present in the first group but are completely absent (below some E-value threshold) in the second group?

Or is there another tool that can do this?