Of course it's different. It's odd that you can't, or won't see that. Starmer is an ineffective prime minister who was leaving the UK wide open to quasi-fascistic far right government (Reform), something rejected by c 70% of the electorate. If Burnham hasn't stood against him, someone in the PLP with far lower national approval ratings would have unseated him and the chaos would have continued. At least now we'll have a credible government which can hopefully stop right wing populism from destroying our democracy. Burnham didn't stand down in his own constituency; he stood as a candidate for a vacant seat which is entirely valid.
Farage is trying to subvert democracy, setting up a false distinction between democracy as represented by Reform (🤣) and some shadowy elite who'd do anything to stop the truth-bearing Reform in order to support their own nefarious agenda. In doing this, he hopes to minimise his poor conduct and make all the trouble he's in disappear.
The joke is that Burnham has governmental experience and was incredibly present and effective in Manchester whereas Farage does the lesser part of bugger all for his constituents because he's too busy jetting off to the US to sample the taste of Trump's anus (and, for all we know doing the same in Russia with Putin).
So please. Stop your banal comparisons. The only people you're fooling are the already gullible.