Game mode: [Singleplayer]
Crude Planter says it grows plants slowly.
Planter says it grows plants at a regular rate.
Improved Planter says it grows plants quickly.
I tested all three planters with five crops each. Every crop grew at exactly the same rate regardless of which planter it was in. The yield for each crop was also exactly the same across all planters.
x10 Plant Fiber
x25 Leavening Agent
x50 Highland Berries
The only difference is inventory space and the texture.
As a side note, the yield for plant fiber is a joke as it takes 5 just to make the required compost.
Steps on how to reproduce issue: