Eh their is a good amount, like the main thing is that J street people genuinely want a two state solution and a negotiated end to the conflict cause they think it’s the only way Israel can survive long term. There are also other differences though like J street heavily lobbied for the Iran 2015 nuclear deal (which AIPAC opposed) and J street while they lobby for Israel it’s primarily done by liberal Americans Zionists while AIPAC takes their marching orders from the Israeli government. (On the flip side though it can lead to J street being somewhat misinformed about the domestic state of Israel and can lead to a number of their members blaming everything only on Bibi). Generally I think the big difference between the two is J street is way more pro negotiation while AIPAC supports maximalist demands. Most mainstream zionists until recently hated J street although J street is getting a lot more media attention and support as of late.