Now, figure out which drive is which: hdparm -I /dev/sd[ab]
The output from that ought to show tons of data for both the old and new drives, one of which will be /dev/sda, and the other /dev/sdb.
Make certain you know which is which, and ask again here if in any doubt.
Here's a simpler way to accomplish that, without having to scroll backwards through 100s of lines of hdparm output. Two commands to dump the model numbers:
cat /sys/block/sda/device/model
cat /sys/block/sdb/device/modelThe first line above will identify
/dev/sda, and the second line will show
/dev/sdb-ml