what is the difference between" I have got a little petrol" and "I have a little petrol"?

Both the sentences give same meaning. There is no difference. I have got an elder brother I have an elder brother. 'Have' and 'have got' have the same meaning when they refer possession and belongings. They render different meaning when 'have' is used as a verb. I have Lunch at 2 p.m (action) I have got Lunch at 2 p.m (received) Moreover 'Have got' can only be used in present tense.