[teamonkey]

In British English there are specific meanings. “Firing” is a general term for getting rid of staff. “Sacking” is getting rid of staff because they have done something wrong.

“Group” can be used when talking about a large organisation as a whole, rather than a smaller component or subsidiary.

So the FT is explicitly drawing attention to the argument that the people were fired because of something they did (attempting to unionise) and that that decision was made or sanctioned by Apple at the top level (not some regional CEO or middle manager).

[jp57]

One might think that they're using "group" because Apple is a multinational with subsidiaries in various other countries. But the article is in fact about a dispute between the US company and some of its US employees.