Adding -ly

[jack]

What do these mean?
1. He is running very slowly.
2. He is running very slow.

[Tdol]

The first describes the way he is physically running, while the second suggests that he is behind with his schedule, IMO.

[jack]

What do these mean?
1. He is running very slowly.
2. He is running very slow.

What If I mean that person is running for both of them, do they mean the same thing for both sentences?

These are correct right? They're not conditionals right? What do these mean?
1. What If I mean that person is running for both of them, do they mean the same thing for both sentences?
2. What If I meant that person is running for both of them, do they mean the same thing for both sentences?

[Casiopea]

I agree with tdol's suggestions. 'slowly' is an adverb, and it modifies the verb 'running', whereas 'slow' is an adjective, used in place of 'late/behind schedule'; e.g., He is running late/behind schedule. Since 'slowly' and 'slow' have different functions, they do not mean the same thing.

1. 'mean' as a present fact; 2. talking about the past.