Moon Lord is one of the hardest boss fights in gaming, While elder dragon is not. People can steal and grief in Terraria, While in Minecraft you can easily prevent this. There is a high chance at night for several strong monsters to appear. You can not control this at all. In Minecraft bosses can only spawn when you want them too.
In master mode things do way more damage and have more health. There are way more bosses and they are so much harder than in Minecraft. That's basically all I have to say so I'm just going to say random stuff so I can get past 50 words and done
You have to build shelter right away. Zombies and eyeballs come at night and even slimes can kill you quickly. In blood moons the zombies knockdown doors and have frenzy.
You are weak and even if you get iron your are still weak. Magic takes time to reload and all the good stuff is protected by stronger monsters. Until you get magma or meteor armor you will die many times.