going to, will

Is it true that in most cases, when the word 'tomorrow' is placed at the beginning of a sentence it will be followed by "will' and when it is placed at the end of a sentence it is preceded by 'going to'?

'Tomorrow, we will become one family.' instead of 'Tomorrow, we are going to become one family

'We are going home tomorrow' instead of   'We will go home tomorrow'.

I'm trying to understand the difference between 'going to' and 'will' if there is any.

Tomorrow is tomorrow.  It's always the future.  I don't think the placement in the sentence has much (if any) effect on which future 'tense' is used.

'We are going home tomorrow' -->  This is not an example of the 'be going to' future.  This is the present continuous tense of the verb 'go'.  The present continuous is used to talk about definite, fixed plans in the near future.  We are very sure about the future here.

'We will go home tomorrow' --> The word 'will' can be used in various ways:

- It could be used to make a simple prediction of what is probable (but not sure) in the future.

- It would also be what you might say at the moment you make the decision to go home tomorrow. (After the decision has been made, you would have to use a different future tense to talk about your plan to go home tomorrow.)

- It might also be used to indicate a willingness to go home tomorrow or to make a promise to go home tomorrow.

Which of these usages your sentence is would depend on the broader context.