Exodus 5:1 "Afterward Moses and Aaron went and said to Pharaoh, "Thus says the LORD, the God of Israel, 'Let my people go, that they may hold a feast to me in the wilderness.'"
Here YHWH calls the people of Israel HIS people.
Exodus 33:1 "The LORD said to Moses, "Depart; go up from here, you and the people whom you have brought up out of the land of Egypt, to the land of which I swore to Abraham, Isaac, and Jacob, saying, 'To your offspring I will give it.'"
Here YHWH merely says that Moses brought them out of Egypt. He doesn't say that the people of Israel belong to Moses, because they don't; they belong to God.
Also, just as a side note(hopefully this is of some relevance to the question). The scripture doesn't say that Moses brought them out of the land of Egypt entirely on his own because we know that just isn't true; without God, none of what Moses accomplished would have been accomplished. But Moses certainly played an essential role. God could have just as easily said, "...you and the people whom you and I have brought up out of the land of Egypt..." But nowhere does it say that God is required to say that, and nowhere does it say that if He doesn't do that it means that Moses must've done it all on his own.
Once again, however, there is no contradiction between Exodus 33:1 and Exodus 5:1; the former refers to Moses bringing God's people out of Egypt(due to the vital role he played in such a feat being accomplished), and the former refers to the people of Israel being YHWH's people.