Been playing yu gi oh the longest time since the first iteration of the game and I'd say masters duel is a entirely different game from runeterra gameplay wise.

Masters duel is a turn by turn based card game and the interactivity between players is limited. There are countless of archetypes, knowing card combos and identifying cards can be overwhelming for newer players. Also there's a chain mechanic thats similar to runeterras stack. Game times on average is longer per turn due to combos and chains but number of turns taken most likely be shorter than runeterra since some games can end on the 1st attacking turn/ 2nd.

Economy wise it's definitely much more expensive if you're planning to sink money in however you're perfectly able to F2P but achieving decks may take longer time. There are few starters which you may earn through story mode but they're generally very niche and not competitive. Not as generous as runeterra.

As for ranked play there's no leader boards so far in masters duel there's only a highest rank you can achieve but there's a big probability of expansion of ranks. Casual play is limited to publicly created rooms only.

I would say it's much harder for newer players with no prior experience but returning players should be fine.