What is the difference between
We do have?
Has it same meaning or different meanings?
In positive statements the use of the auxiliary do is always optional, and it conveys emphasis (usually contrastive).
The basic objective meaning of the statement is unchanged, but emphatic do adds a connotation of "contrary to what you thought/you asked/I suggested/somebody said".
Examples of emphatic do:
Have you any coffee? No, but we do have hot chocolate.
Have you any coffee? I don't think so, but I'll check. Yes, we do have some!
We haven't got a golf course here, but we do have a pool with a waterslide.
We do have has more weight to it.
Do before a verb is often used for adding emphasis.
The meaning is the same but the two constructions are typically used in different contexts.
We have..... is a simple statement of whatever items someone may have to offer. If a customer were to ask a greengrocer what fresh products were available, the latter might reply: **We have lettuce that just in, freshly picked cabbage, newly delivered cauliflower....and so on.
However, if a customer were to walk into a shop looking for a specific product, say a replacement alternator for a car, the salesperson might reply:
Well, we do have one in stock but it's not brand new. It comes from a newish car that was written off in an accident.
The construction we do have.... is typically followed by some comment or condition or limitation that might affect the sale.
Equally, a headmaster might tell a parent looking for a place for a child:
We do have one more place but it's supported by a bursary, which means that your child will have to meet certain conditions.