The easiest Chinese character would be numbers,
one → “一“
two → “二”
three → “三“
（No, four is not four straight lines.)
the hardest Chinese character, I assume you mean the Chinese character with the most strokes. There’s some debate on that.
So there are over 85 thousand Chinese characters. But you only need 3500 characters to handle the most everyday conversations.
When people talking about the most difficult characters, the ones they pick are almost always one of the “dead” characters outside the 3500 characters.
Some people say the most difficult Chinese character is this word:
I have no idea what it means, how to pronounce it. and I have zero interest in finding out. (so please do not comment and tell me about it. I do not care).
Or this character
The only reason I know about it is that it’s the name for a popular noodle dish.
Or this word:
Again, no idea what it means but I assume it has something to do with dragons.
Anyway, as I said, you seriously don’t need to worry about any of these.
I think the most difficult regular words… maybe 囊？