在日常交流中，可以忽視它們的區別，只有在一些細膩的表現中，才需要注意。

as if純粹表示比喻，而as though則含有一點說話人的主觀上的肯定。

以下對比

He is talking crazily as if he were on drugs.

He is talking crazily as though he were on drugs.

前者只是像吃了藥，而後者說話人是真的懷疑他吃了藥。

Tim writes as if he were left-handed.

Tim writes as though he were left-handed.

前者只是說Tim像左撇子，而後者說話人是真的懷疑Tim是左撇子。

We danced as if it were the last time.

We danced as though it were the last time.

前者的描寫相對冷淡，而後者則帶有說話人的主觀，認為這真的是最後一次，帶有一點惋惜的意思。

另外，as if可以用作強烈的否定，而as though則不行。

Do you like him?

As if.

=It isn"t as if I like him. （我看上去像是喜歡他嗎）

×As though

這是因為as though帶有說話人的主觀肯定，跟所表達的意思有矛盾。