Ocular dominance
Ocular Dominance is a naturally occurring phenomenon. One eye is naturally dominant while the other is non dominant. Much the same as hand dominance. This means one eye is usually going to see just a bit better, and improve a bit faster than the other. A difference of between .25 and .50 is quite common.
Many opticians compensate for this by adding extra correction to the non dominant eye. In most cases this compensation is unnecessary. If your "prescription" has this compensation, then at some point (generally after 2-3 spherical reductions) you will want to work toward equalizing. If this is your first correction, or the first time it has been present in your correction, you might consider not adding this complication to your focal plane at all.
It is strongly advised to wait until the non dominant eye catches up, before introducing a new reduction. You might help this along with some moderate patching.
This student's Tag-In Method may help you ensure that you are getting equal stimulus for both eyes.
See Also
References
The EndMyopia Blog:
https://endmyopia.org/the-diopter-ratio-trap-dont-favor-one-eye/
https://endmyopia.org/reducing-diopter-ratio-diy-patching-solution-pro-topic/