HAWQ is same as Greenplum, only underlying storage is hdfs,
One way is You can create a externale(writable) table in HAWQ which will write your data into a file, now after this you can create a external(readable) table in Greenplum which will read data from that created file
Another way You can copy from one server to another using Standard Input/Output, I use it many times when required to puch data from development environment to Prodcution or vice-versa
Another way You can table a backup using pg_dump/gp_dump for particular table/tables then restore using pg_restore/gp_restore
Thanks