As far as I remember and understand, OpenBazaar is more like decentralised Ebay/Etsy.
Whereas Bisq is a decentralised currency exchange. You use your own crypto wallets, bisq does not provide you with one, and therefore, you do not have these lock-down-out problems people have had with Steem and others recently. Your coin is your coin.
Good comments on this post from you @leoplaw