Over 20 variants for the biomes.
M - Biomes with an M variant are much rarer than any other variant. Those are more mountainous versions of their normal biome counterpart.

• Extreme Hills M
• Taiga M
• Roofed Forest M
• JungleEdge M
• Birch Forest M
  has taller birch trees than usual
• Cold Taiga M
• Extreme Hills+ M
• Savanna M
  has grassless dirt and mountains that can generate above the clouds and up to y=220.
• Savanna Plateau M
• Swampland M
• Jungle M
• Mesa Plateau M
• Mesa Plateau F M
• Desert M
  has patches of water unlike normal deserts

Plateau - Biomes with a Plateau variant are like the hills technical biome, but flattened at the top

• Savanna Plateau
• Mesa Plateau
• Mesa (Bryce)
  A rare variant of the Mesa biome which works similar to ice spikes with tall clay spikes generating from the sandy mesa floor.
  Hills - More technical hills biomes have been added to fit with the new biomes.
• Birch Forest Hills
• Cold Taiga Hills
• Mega Taiga Hills
  Beach - New beaches separate certain biomes from oceans and rivers.
• Stone Beach
  is composed mainly of Stone and often generates between an Extreme Hills biome and a body of water.
• Cold Beach
  is composed of Sand with a layer of Snow on top. Usually generates between a cold biome, such as Ice Plains, and a body of water.