Quite different setups if you ask me - and it's hard to separate plan from personnel.
Thompson/Hird generally included forwards like Howlett, Chapman, Monfries, Cooney (and at times guys like Hardingham). Small marking players with little to no pace to them, but who could compete as contested midfield players.
Now we pick 3 quick small forwards who couldn't win a midfield contest to save their life, but are good at crumbling, goalkicking, pressuring, and can torch teams if they get the ball on a wing.
That's a personnel difference but also a strategic decision - forward line is for forwards, not for your 3 next best midfielders.
And the other big personnel/strategic change is someone finally recognising that PACE MATTERS
Almost all the guys who've come in this year - Stewart (for his height), Bellcho (compared to Leuenberger), Green, McKenna, McGrath - have one common feature. SPEEEEEED.