Pitcher_crop makes its farmland a full block. All other crops do not.

To reproduce... stand on farmland and run this command:
/execute if block ~ ~ ~ minecraft:farmland run say true

It will always be true on bare farmland, and in any other crop, because the player is standing in the same block as the farmland... it is not a full block.

It will not be true if standing in pitcher_crop as the player will be standing higher up in the crop itself as the farmland is a full block under pitcher_crop.

You can also detect this by simply walking across farmland. When entering into pitcher_crop, the player will visibly bump up 0.2 blocks on top of the farmland as if it were a full block in height, and bump back down 0.2 blocks when exiting the pitcher_crop into other farmland.