As 和like作preposition

雖然as 和Like都係preposition, 看以下兩句:

She spoke as a lawyer.

She spoke like a lawyer.

兩者的as和like都是介詞,但有何不同?

第一句,意思是:她作為一個律師發言.

第二句,意思是:她像一個律師發言.