What's the difference between this and here in English? What is this? What is this?

Tell me about my understanding, although several people upstairs are very reasonable.

This is an apple. This is an apple. This is the most conventional statement. Demonstrative pronoun +be verb+article+noun

It is also the most common statement tone: this is an apple, which is used to judge something.

Here is an apple. Here is an apple. Look carefully, it is an inverted sentence. The normal word order is: an apple is here. The reason why it is advanced here is to attract the attention or emphasis of the other party. Please imagine a scene: I ask you for an apple, and you happen to have one in your hand. Are you pointing to that apple and saying, This is an apple, or pass me the apple and say, Here is an apple. Obviously, the answer is the latter.