Dime-store answer: if buttons aren't needed, don't use them. That being said...
Q: ...different contexts. What exactly is the distinction between [A and B]?
A: They are designed for the same context, forms.
"Forms" is too broad a context to determine even a subjective preference between options A and B—a qualitative measure—let alone applying the comparison in quantitative user testing, i.e., measuring various user cognitive and performance metrics accomplishing a list of tasks.
To gain a usable response, start with the "option B" scenario—partly to reduce the measurable differences between A and B from many to one, but also because Option A is confusing, e.g., are the radio options exclusive, are the checkbox options inclusive?
The form context presented here is (apparently) the part of a larger form where clients scheduling a consultation indicate how and where they like to meet.
The client has the option to meet online, or at a company office. If an office consultation is selected the client then selects the office location. Both the online/office selection and the two location selections are exclusive.
Option A
Incorporating radio button controls and border highlighting to indicate selection:
Option B
Relying solely on border highlighting to indicate selection:
To measure the clarity of instructions show unselected presentations:
Considering...
The primary question—"Where would you like to meet?",
And the physical limitation of not being able to be in two locations at the same time,
...strongly suggests the choice for both questions are exclusive—i.e., you can only select one making Option B effective and slightly "cleaner", and radio buttons not necessary to communicate exclusivity.
However, consistency of form-wide use of controls is a significantly greater priority over "effective and clean" in any portion. Therefore, an analysis of the entire form is necessary to ultimately decide if inclusion of radio/checkbox controls is needed to improve the form's UX.
Clarify the "Option A" presentation in the question, and the rest of a representative form in your project, with a specific scenario then present options with and without buttons ready for qualitative and quantitative analysis.
