Pharaoh is a title for the Egyptian ruler, not a personal name.
The origin of the word Hebrew is not clear. When Egyptians and Philistines used this word for the Israelites, it may have been an insult. It likely described a low social class that other people considered unimportant or inferior.
Whatever the number of Hebrew people, there were clearly more than two midwives for the whole nation (see study note on 12:37). Shiphrah and Puah probably represent the entire group.
The differences between Pharaoh and the midwives were very clear:
Pharaoh had great political and military power, but the midwives had none.
Pharaoh had high status, but they had little.
Pharaoh was a man from the ruling people, and they were enslaved women.
Pharaoh was rich, and they were poor.
Pharaoh could have easily forced them to obey, but they did not give in.