sayとtell (1)

that is (to say) すなわち

What do you say to ~ing? ~するのはどうですか

You can say that again. まったくその通り

tell off ~, tell ~ off ~をしかる
= scold ~

to tell (you) the truth 実を言うと

sayとtell (2)

as the proverb[saying] says[goes, runs, is] ことわざにもある通り

needless to say 言うまでもなく

It goes without saying (that) ~ ~は言うまでもない
= Needless to say, ~
go without ~ ~なしですます

tell (~) a lie (~に)うそをつく
= lie (to ~)

tell A from B AとBを区別する
= distinguish[know] A from B

tell the difference 違いがわかる