Simple & progressive

sitifan What's the difference in meaning between 1, 2 and 3, 4 respectively?

This doesn't compute.

Do you want to compare 1 with 2, and 3 with 4; or do you want to compare 1 with 3, and 2 with 4? (the latter, I suspect)

There's a way to say this using "respectively," but this isn't it.

Best wishes for a Merry Christmas and a Hap

1. The man drives the car every day. He has this habit.

2. The man drove the car yesterday. Report of a past event.

3. The man is driving the car every day. This one is a bit anomalous without context. every day doesn't seem to fit very well. these days might be better.

4. The man was driving the car yesterday. Report of a past activity.

Sen

Generally speaking, a reduced relative represents only a progressive form.

1. The man who drives the car every day is my brother.
2. The man driving the car every day is my brother.
3. The man who drove the car yesterday was my brother.
4. The man driving the car yesterday was my brother.
Why do 1 and 3 have the same meanings as 2 and 4 respectively?

"Every day" and "yesterday" further qualify the time frames of the verb.

[1a]The boy who brings the milk every morning has been ill.
[2a]The boy bringing the milk every morning has been ill.
Does [2a] correspond to [1a]?

sitifan[1a]The boy who brings the milk every morning has been ill.
[2a]The boy bringing the milk every morning has been ill.
Does [2a] correspond to [1a]?

No. "Who brings" focuses on the subject, "boy." "bringing the milk" focuses on the action.
The implication in (1) is that the usual boy has not been bringing the milk during his illness.