What is the difference between advantage, merit, and benefit?

Can you please explain the differences between these three words?
Because I always misuse them when I am writing English.

I have read a few sentences:

The merits of the new health program are gradually being recognized.

Don't you think merit and advantage are similar?

The main advantage of using word processors is the amount of time you save.

So time-saving is something that puts word processors in a better position than other machines? Can't I use benefit instead?

Solution 1:

Inspired by the comments, I essay a simple analysis by Venn Diagram of the set of meanings of these words. I have taken a few key definitions from the Cambridge Dictionary but do not repeat them tediously for you here.

for one example:

Cambridge Dictionary

There are areas of synonimity but there are also areas of separation of meaning. I suggest that this shows the overlap of benefit and merit as regards goodness; the helpful overtones of benefit; the feeling of praise and judgement of quality in merit; the commonality of advantage; and the unique overtones of comparison that are associated with advantage.