https://support.communitybrands.com/hc/en-us/community/posts/30727102961037--888-829-1467-Is-it-worth-upgrading-to-economy-Plus-on-United

In contrast, upgrading to Economy Plus provides more legroom and a seat closer to the front but does not include additional baggage allowances. Unlike Premium Economy, which has its own cabin, Economy Plus remains part of the main cabin.