goldenboy, yes, there is a difference, we'er going more into it here, I mentioned the Diaspora above, when the Jews were dispersed by the Romans, the majority settled in Spain, some went to Eastern Europe, Russia etc,
Over time, these two groups formed their own style of worship, while keeping to the main points, the two names you mentioned, relate more to the style of worship, Ashkenazi (note the last four letters), and Sephardi.
Ashkenazi use the Eastern European form of worship, and Sephardi the Spanish.
All Jews, regardless of where they come from, use one or the other, this also incorperates different foods.
As for genetic differences, they are the same differences as any two people who come from different parts of the world. The majority of Jews nowadays, genetically, have no relationship to Arabs at all.