1 We sold the wooden tables and the chairs in the garden.
2 We sold the wooden tables, and the chairs in the garden.
Does the comma change anything?
I think '1' is ambiguous. We can't tell if 'the wooden tables' were in the garden or not. The comma in '2' seems to make it clear that they were not.
In #1 we don't know whether the tables and chairs were in the garden usually (garden furniture) or whether we held a sale in the garden.