A grammar is context-free if all production rules have the form: A (that is, the left side of a rule can only be a single variable; the right side is unrestricted and can be any sequence of terminals and variables).
We can define a grammar as a 4-tuple where V is a finite set (variables), _ is a finite set (terminals), S is the start variable, and R is a finite set of rules, each of which is a mapping V
regular grammar is either right or left linear, whereas context free grammar is basically any combination of terminals and non-terminals. hence we can say that regular grammar is a subset of context-free grammar.
After these properties we can say that Context Free Languages set also contains Regular Languages set