In the English Vocabulary Profile, the pictured item “unless” has one level = B1.
18 CONJUNCTIONS subordinating B2 3 wide range of simple subordinating conjunctions (‘once, whereas, unless, except (that) provided (that)’), to introduce a subordinate clause.
Getting to work by car is comfortable, and faster unless you are caught in a traffic jam.
Unless the situation improves, we will be forced to try a new supplier.
In these B2 examples above, we can see that there is present simple passive and present simple active. The time reference in the first is the present and the second is the future. There is no reference in the explanation to time, so this conjunction is considered to be a general marker of B2 complexity. However, when we move to B1 in the CLAUSES category, there is no real difference in the examples. Subordinating vs coordinating might be the main difference noticeable in the comma usage to some extent and the multiple clauses. The term ‘exception” does not really make a difference semantically since all examples seem like “exceptions”.
57 CLAUSES conditional B1 USE: ‘UNLESS’, EXCEPTIONS ‘unless’ + present simple to talk about an exception, with present and future reference.
I think I am going to pay by cash, unless you accept credit cards.
If I were you I ‘d go to work on foot, unless it’s far away from your house.
But unless you do some sports activities you will gain a lot of weight.
One could make up their own criterion based on the examples and make pronouns as subjects and active sentences as B1.