I’m visiting my friend tomorrow.
They are coming to our house on Saturday.
What are you doing tonight?
We can use the present continuous to talk about arrangements (plans which you have organised) in the future.
My brother is playing football with his friends tonight.
I’m going to the cinema at the weekend.
Are you having a party for your birthday?
We usually use the present continuous when the activity has been arranged. We usually use ‘going to’ for a plan which hasn’t been arranged.
I’m meeting Emma after school. (I have talked to her and organised the time to meet.)
I’m going to watch TV after school. (This is my plan but I haven’t organised it.)
We say... We don’t say...
My grandma is visiting us next week. (NOT My grandma visits us next week.)
We’re going to Spain for our next holiday. (NOT We go to Spain for our next holiday.)
Is he helping his mum tomorrow? (NOT Is he tomorrow helping his mum?)