When you thank someone for something, you express your gratitude to them for it.
感谢
When you express your thanks to someone, you express your gratitude to them for something.
谢意 They accepted their certificates with words of thanks. 他们接过证书,同时表示了谢意。
I can find my own way home, thank you.
我自己能找到路回家,谢谢。