Well without getting technical, lets just say that its always been called SSL for decades, but all the SSL protocols were found to be completely insecure, so have been abandoned for a new protocol called TLS.  

TLS is SSL successor and eventually the term “SSL” will fade away as people get used to seeing HTTPS or TLS.  Both TLS and SSL were protocols that enabled HTTPS (as opposed to HTTP).  

HTTPS stands for Hyper-Text-Transfer-Protocol-Secure - its the more important term since the underlying security protocols (ssl/tls) can change as vulnerabilities are found.  

So lets just call it HTTPS!