Not the same likes. At some point Facebook added a "like" button in the Messenger, which immediately sends a slightly-different thumbs-up. On Android it replaces the "send message" button when you haven't entered any text yet, and it also features as an action if you expand the new message notification. Both of these make it super-convenient to use it.
(Though personally, I don't use it at all; a thumbs-up icon feels disrespectful for me, I prefer to acknowledge by typing out "OK" or even a smiley.)
(Though personally, I don't use it at all; a thumbs-up icon feels disrespectful for me, I prefer to acknowledge by typing out "OK" or even a smiley.)