Confused,crossing networks order vs Electronic communications networks

what are the differences between these two?


Price discovery is the difference

If my memory is right, electronic communciations networks work on an auction-type system while crossing networks use order books to match trades at fixed times during the trading day.

My understanding is that ECN is just a alternative type of exchange while you trade normally, 100/1000 shares; while crossing nestwork is specifically for transacting larger share amount, often with buyside desks directly; some crossing network actually are only available to buyside clients. Think of it as the old block desk on the street.