'Is' and 'being'

Tom is very stubborn.
Tom is being very stubborn.

Is there any difference between these two sentences?

There is actually a subtle difference between these two sentences.

'Tom is very stubborn.'

This sentence talks about a general quality of Tom. The speaker means that Tom is always a stubborn person, and he is stubborn in the past, present and future.

'Tom is being very stubborn.'

The speaker means that Tom is stubborn at this time (the time of speaking).

So, can you now tell the difference between the following two sentences?

1. You are being rude.
2. You are rude.