While both muesli and granola are a mix of grains, seeds, nuts and dried fruits, the main difference is that granola is sweetened with honey or maple syrup and is baked. Muesli is not baked.
They each are regarded as a healthy breakfast.
I was recently very excited to receive an invitation to talk on The Gut-Mind Collective Podcast, with my good friend Merryn in East Gippsland, about having coeliacs disease and the role my kitchen garden played in helping recover.