My search yielded the below:

Differences between pits and seeds:
Seeds are ovules containing embryos, while pits protect the seeds until growth time1.
Seeds can be many or one in a fruit, while pits are always one1.
Pits are contained in cherry fruit, plums, peaches, and dates, while mangoes, oranges, and apples have seeds1.
Pits are part of the whole fruit, while seeds can be by themselves2.
Pits are made of different layers, while seeds are simpler2.