if vs unless

[hela]

Dear teachers,

Do you see any difference in meaning between:

I'll be back by the weekend, unless there is a train strike.
and
I'll be back by the weekend, if the train drivers aren't on strike.

Does unless suggest that the action is unlikely to happen,
whether if suggests that the action may happen ?

Many thanks,
Hela

[Rusty]

Dear teachers,

Do you see any difference in meaning between:

I'll be back by the weekend, unless there is a train strike.
and
I'll be back by the weekend, if the train drivers aren't on strike.

Does unless suggest that the action is unlikely to happen,
whether if suggests that the action may happen ?

Many thanks,
Hela Unless sets a condition that would change the main clause from positive to negative:
I'll be back by the weekend, unless there is a train strike. =
I won't be back by the weekend if there is train strike.

Or negative to positive:
I won't be back by the weekend unless the train strike ends. =
I will be back by the weekend if the train strike ends.
Unless does not make a suggestion, it states a condition.
If states a condition that may or may not happen.