There is no ‘regardless of time period’, that’s the absolute foundation of the difference between the two. The laws/guidance across 2020/2021 varied a lot. We all lived it, it’s hilarious that anyone would try to rewrite history to this extent. Boris broke laws when there was little to no leeway for bubbles of any description, following vaccinations there were elements that were slightly more relaxed such as in work settings.
But the main difference is that it is harder to prove Sir Keir was not just taking a break from work, as he insists, whereas it is hard to conceive that a pre-arranged birthday party, complete with cake, was anything other than a social gathering
https://inews.co.uk/news/politics/beergate-how-keir-starmers-lockdown-beer-differs-from-boris-johnsons-covid-rule-flouting-birthday-party-1608611
All of this pales against the fact that as Prime Minister imposing heavy restrictions on an entire country Boris completely shirked his responsibilities as someone in a position of such power to abide by his own rules.
Regardless of your own personal motivations, Kier Starmar didn’t and doesn’t carry that same responsibilities purely because his position doesn’t hold the same power and responsibility.
The nuances are pretty obvious to most, alongside the fact that two wrongs wouldn’t make a right. It’s quite simply irrelevant to any analysis of Boris’ behaviour. To still be banging the same drum this far down the line is churlish playground bollocks.
If you’re that bothered about Kier’s behaviour put your efforts into arguing for that instead of lazily relying on that as a defence of someone else’s behaviour. If you take the stance that Boris did nothing wrong, then neither did Keir by your own standards so what’s the bloody point of raising it?