According to the Open Source Initiative (the folks who control whether things can be officially certified as "open source), it basically is the same thing as Free Software. In fact, their definition was copied and pasted from the Debian Free Software guidelines.
Open source ≠ Source availiable
Example of non open source programs with source code https://en.m.wikipedia.org/wiki/List_of_proprietary_source-available_software
Open source ≠ free software
According to the Open Source Initiative (the folks who control whether things can be officially certified as "open source), it basically is the same thing as Free Software. In fact, their definition was copied and pasted from the Debian Free Software guidelines.
You are talking about free softwares there are nonfree licenses which provide source code