What are the big differences between MySQL and SQL Server?

Hi,

I did programmed only with MS Access and I would like to know what are the big diffences between MySQL and MS SQL Server, for me to choose to best one.

Does MySQL and SQL Server work like MS Access, you do your database on your computer and then you use WSFTP and your internet connection, to send it on the server?

Should I use MySQL and SQL Server, or I should use only one?

Bye

Simon Baillargeon