x = 5 + 10 is an expression but with when followred by semicolon x = 5 + 10; its called an "expression statement", This makes "“every expression can also be used as a statement" true, but then they will not be strictly called as "statement" but rather called as "expression statement" as statements are  are constructs that perform actions or control flow and do not necessarily yield a value, like if, for, or function declarations, so my takeaway and simple solution to tell if given piece of line is statment or expression is**,
[if you can put it in the console.log() without error/which gives some meaningful result  then its an expression and when you place that content with a semicolon then its technically called as "expression statement" anything else is just pure "statement" ]**