That's a meaningless question, as SQL and mySQL are different kinds of things. They aren't comparable.
As pointed out by others, SQL is a generic term meaning "Structured Query Language". There is also are ANSI and ISO standards for SQL that define the syntax of a specific SQL language.
Many database servers implement or partially implement these standards, and most extend them in some way.
Many database servers use the term "SQL" in their name, MySQL being one of them.
"SQL" is not an alternative to "MySQL". MySQL isn't better or worse than "SQL", as MySQL is a program you run on your computer, and SQL is a language specification.
Microsoft has a product called "Microsoft SQL Server", and some here apparently thought that that is what you meant.
To answer your question literally, then, yes, there's a huge difference between MySQL and SQL, since they aren't even the same kind of thing.