difference - "If he were to do" vs. "if he did"

What is the difference in the meaning of following sentences?

1. 
   
   

   If Tom were to do my homework, I would watch a film.

   
   


2. 
   

   If Tom did my homework, I would watch a film.

   
   

I know that both of these questions express unlikely or imagined condition. I'm not sure but I think. There's is difference in the meaning between two sentences. Here is my opinion:

1. 
   
   

   In the first sentence, the speaker thinks that it's impossible for Tom to do his homework or Tom isn't able to do his homework or Tom is a baby. So, the speaker is imagining a impossible thing.

   
   


2. 
   

   In the second sentence, the speaker thinks it's a bit possible for Tom to do his homework.Tom is the speaker's friend and Tom is able to his homework but he isn't willing to do. So, the speaker is expressing his imagination and saying "If Tom did my homework I'd watch a film".

   
   

For more clearification of my openion i would say: I'm not sure but I'm just guessing the possible meaning of those sentences like this:

both sentences are all about imagination but first sentence indicates impossible imagination and second expresses unlikely but expected imagination. AM i correct?

Am I correct in my opinion ? If not, what is the correct meaning? Please explain it in details.