Schema's vs Single Database with prefix on tables

We are using Postgres and we are with a issue. We have splited our tables by domain and each domain has a separated database, but we are trying to change it to a single database model. We have two options, create the same database in a single schema and add a prefix on each database domain or create a schema for each database (we have about 15 different models). In this approach we still want to do some joins and other queries cross schema, but we don’t know what would be the best approach :) Could you help us to know what would be the best approach ?

* having just one database with one schema and all domain databases with a prefix

* having a schema for each domain (15 domains) with the domain databases (+/ 20 tables) (knowing that we do cross schema queries)