Most assuredly, there is a difference between angels and demons. Demons are disembodied evil spirits while angels can take on physical bodies.
Demons are disembodied and seek to inhabit an earthly body. There are examples of this and Jesus commanding them to leave their host body. Mark 5:8, “For he said unto him, Come out of the man, thou unclean spirit.” Jesus allowed the demons to enter a herd of swine. Mark 5:13, “And forthwith Jesus gave them leave. And the unclean spirits went out, and entered into the swine: and the herd ran violently down a steep place into the sea, (they were about two thousand;) and were choked in the sea.”
Jesus cast out an evil spirit from a man who couldn't speak. To the Jewish leadership, it was impossible to cast out an evil spirit until that spirit had identified itself. The Pharisee did not take kindly to this. Matthew 9:34, “But the Pharisees said, He casteth out devils through the prince of the devils.” This led to the discourse by Jesus in Matthew 12 concerning a kingdom divided against itself will not stand. By stating that Jesus worked through the devil, they had committed the unpardonable sin.
Angels are powerful and serve God and can take on the form of a human being as evidenced by the Bible:
Genesis 19, fire and brimstone could not destroy Sodom and Gomorrah until Lot his family were removed from danger by two angels.
Daniel had a vision of the archangel Gabriel, God's messenger, and provided this awesome description of the physicality of an angel of God. Daniel 10:5-6, “Then I lifted up mine eyes, and looked, and behold a certain man clothed in linen, whose loins were girded with fine gold of Uphaz: 6 His body also was like the beryl, and his face as the appearance of lightning, and his eyes as lamps of fire, and his arms and his feet like in colour to polished brass, and the voice of his words like the voice of a multitude.” Gabriel had a message for Daniel but was hampered for 21 days by the Prince of Persia and required the help of the archangel Michael, God's warrior. The Prince of Persia, an agent of Satan, a manifestation of the fallen angels?
Two angels appeared at the empty tomb, Luke 24:3-4, “3 And they entered in, and found not the body of the Lord Jesus. 4 And it came to pass, as they were much perplexed thereabout, behold, two men stood by them in shining garments”
The Rephaim were the descendants of fallen angels, giants, such as Og king of Bashan whose bedstead was nine by four cubits.
Deuteronomy 20:17-18, “But thou shalt utterly destroy them; namely, the Hittites, and the Amorites, the Canaanites, and the Perizzites, the Hivites, and the Jebusites; as the LORD thy God hath commanded thee: 18 That they teach you not to do after all their abominations, which they have done unto their gods; so should ye sin against the LORD your God.”
Sadly, the entire land promised to the Israelite's had not been totally conquered and occupied in the time of Joshua, a thorn in the side of Israel to this day.