turn round:

转身，转向；归航；回车道；转变

They told me to stand still and not to turn round.

他们叫我站着不动并且不要转身。

turn around:

转向反方向；(生意或经济) 好转；船只留港

I want to turn around this great company with you.

我希望能与你一起拯救这家伟大的公司。