I always like her. 和 I have always liked her. 的差別在哪裡？如果不好說明，請提供一些例句。

You normally would not say, "I always like her" but you would say "I always liked her" or "I have always liked her."
As for I always like her you might say it in this context. Say you went to a concert to see a singer you've enjoyed for years and have seen in person (in concert) several times. You might comment, after the concert, "I always like her" meaning she always puts on a good show and you like to attend her concerts. But you'd probably not say this otherwise.