Please explain the ps -aef response on RHEL

Please explain the ps -aef response on RHEL

What does pts/2 indicate in the below output. Why there is no such for
other dd processes?
$ ps -aef |grep dd
root 6553672 15073352 3 02:32:19 - 0:01 dd of=/dev/lv01 bs=1024k
padmin 9437410 16515110 1 02:43:32 **pts/2** 0:00 grep dd
root 13828156 11010220 0 02:32:33 - 0:00 dd of=/dev/lv02 bs=1024k
root 14155860 13828156 2 02:32:33 - 0:01 dd of=/dev/lv02 bs=1024k
root 15073352 13762812 0 02:32:19 - 0:00 dd of=/dev/lv01 bs=1024k
root 15532200 15925276 2 02:40:47 **pts/1** 0:03 dd
of=/home/padmin/sample-dd-op bs=1024k