Walking vs Welsh Onion

I went all gungho on onion varieties and purchased both egyptian walking onion and welsh onion. I was wondering if there is any benefit to having both or do they just overlap in terms of flavour, harvest season and culinary use? I am certainly not complaining over variety and I LOVE all types of onions, hence purchasing lots, plus I plan to use walking onion as green mulch/biomass once they spread enough. Was just curious if anyone else has done the same… Hooray for onions, I didnt even mention all the other onion types I have in my seed collection! Hehehe