The difference between the Level 1 plan (which is not explicitly a Masters plan, but doubles as our Masters plan options) is both workout frequency and duration, plan length, and plan rest week cycle (so a lot different!). See https://www.8020endurance.com/triathlon-level-comparison/ for a more detailed comparison.
Always best to start with a lower level and move up than too high and level-down. Of course, with out Level Guarantee you can always switch levels within the same plan distance for free.
If you complete 6 weeks of the Level plan and are saying “this is too easy” it’s time to consider the Level 2 plan.