The differences are primarily cultural. Greek churches usually have Greek food for coffee hour, Arab churches have delicious Arab food, etc. You'll meet a decent amount of Vlads and Yuris in Slavic tradition parishes whereas in Greek parishes it's usually Andrews, Johns, Georges. Arab parishes have a lot of Elias, Georges, etc.
That said, the OCA and ROCOR tend to actually have Vespers on Saturday nights while GOARCH parishes rarely do. Jerusalem Vicariate parishes and ROCOR tend to be the most traditional in terms of liturgical practice; i.e. Confession the day before or day of Communion, Vigil before Liturgy, higher frequency of weekday liturgies, etc. The OCA generally encourages Vespers Saturday nights, followed by Matins or Hours before Liturgy on Sunday morning, but that generally depends on the individual parish.
In terms of music, the OCA probably has the most diversity pulling from Russian, Carpatho-Rusyn, and Byzantine traditions whereas the Antiochians have a rule that they can only use Antiochian chant. The Greeks stick to Byzantine chant almost all the time (except for one parish I encountered that had a large Ukrainian membership and therefore had about half Slavonic chant)
In my travels consisting of both US coasts, the Deep South, and two foreign countries where I actually could go to Liturgy; I personally prefer OCA or ROCOR parishes followed by Jerusalem Vicariate. The Antiochians and Greeks just don't have a strong spiritual life as the norm. I avoid GOARCH parishes not so much because of recent politics (though it didn't help) but because the Greeks tend to be the most chauvinistic about their ethnic backgrounds. I've met enough Greek chauvinists to believe that it is the norm in the GOARCH whereas I've met very few Slavic chauvinists. The last time I attended a Greek parish was six years ago and I never returned - the final straw was they had had an Orthodox singles event for younger adults (20s, 30s - my age) and despite having been Orthodox since I converted in 2006 I was not invited because I'm not Greek (as confirmed by the... person who organized the event. When I reported that to the priest, it was the first time I ever heard a priest swear and he didn't blame me for leaving). A lot of the rhetoric from the Ecumenical Patriarch and his Ukrainian schismatics also seem to suggest that the EP would be happier as an Eastern Catholic Church under Rome. I was Roman Catholic and left the Church. If I wanted to be under Rome again that I'd be Eastern Catholic, but I have zero intentions of being under Rome again and for the EP and his cadre to even think it is a remotely good idea is a slap on the face to the Orthodox Church.
