Replicate data between MySQL servers with a different structure
Not possible.

Master-Master allows writing to both, and, hence, provides no way to make changes during the replication, at least not bi-directionally.

Master-Slave does allow limited flexibility, such as different engine, different indexes, and, in a few cases, different datatypes.  However, you could lose data.  And it could fail depending on whether you are using binlog_format = ROW versus STATEMENT.  ROW is less forgiving.

Would you like to explain the need you have?  Perhaps we can devise a workaround.

OK, maybe it is possible with Triggers, since they don't have to be the same on both Master and Slave.  (M-M is M-S in both directions.)  So, if you can devise a pair of triggers that completely modify the table(s) at the time of writes, and if selects don't stumble over extra/missing columns/datatypes/tables, then maybe you could do what you want.