I think they'll cheerfully tell you that they're making the claim on the basis of replacing 80m units with 120m and 240m units...
It's sarcasm, of course and of course that's what they'll point to, but at the end of the day it's once again yet more spin that is being used to try and cover-up the fact that a number of 8 car EMUs are going to be replaced by 5 car EMUs that will substantially downgrade the amount of people you can fit on the train at peak time, since whilst you will gain a few more seats, you'll lose an awful lot of standing space.
In 2018 the Greater Anglia spin machine was in overdrive, but in the last few weeks it's become something more than spin, with the recent factually incorrect comments from the MD claiming some of the trains were much older than they actually are, they have more fleets than they actually do and that GA as a franchise have delivered new trains before when they haven't and now this.
It's easy to see similarities with Scotrail where Abellio are busy making claims about the railways up there being the best they have ever been, when customer satisfaction and performance figures would suggest otherwise as they are unable to pack up their lofty promises and marketing with the actual operation of their services. I wouldn't be a bit surprised if we saw the same in Greater Anglia.
Still, if the rail business continues to go tits-up for Abellio, I'm sure that they can re-focus themselves as a marketing agency or a PR firm since their skillset is probably suited to that, or perhaps politics would also be a good industry to be involved in, since that is another place where never answering a straight question with a straight answer is useful.