What is the difference between a Stream cipher and a Symmetric Encryption algorithm?
There are multiple ways to do symmetric encryption. The two most popular ones are block ciphers and stream ciphers. So stream ciphers are a subset of symmetric ciphers.

AES and 3DES are block ciphers, not stream ciphers. But if you use them (or any other block cipher) in CTR mode, you can create a stream cipher out of them.

ChaCha20 is a stream cipher, Poly1305 is a MAC (message authentication code) algorithm. Together, ChaCha20-Poly1305 form an authenticated encryption scheme.