Understanding tkprof results in 12.1

Not a tuning question per se, but this seems the best place to ask.

Looking at tkprof results on the same query in an 11.2 SE-1 database vs a 12.1 SE-2 database.

Method:

1) A .sql script file that has a single SELECT statement.

2) connect to database with sqlplus.

3) in different session query v$session to identify the sqlplus session from 2)

4) using the SID and SERIAL# identified in 3), execute 'exec DBMS_MONITOR.SESSION_TRACE_ENABLE($orasessid, $oraser, TRUE, TRUE);'  (this is actually in a shell script, and in addition to starting the trace, creates another shell script to stop it, and another to run tkprof on the resulting trace file)