To me; production would mean "for fruit and/or flowers" and maintenance means "the rest of the time".

That's how I would interpret it, but I'm not an expert on Foliage Pro. I do know it works great! : )

"fruit and or flowers" is like 90% of the year for citrus. I suppose Foliage Pro isn't just for citrus though.

It's not specifically made just for citrus, but it works really well on them. I've had citrus in pots for about 5-6 years now and nothing I've used before Foliage Pro has worked as well.
I've seen a dramatic improvement in both flowering and foliage since I switched. (and no, I don't work for them, lol)

So if it's like 90% of the year, just use the production instructions all year. I wouldn't worry about it.

Barb nailed it, really.
Production is basically the prime growing/fruiting season.

I fertilize everything with Foliage Pro, from peppers to citrus to conifers to succulents. I've also found that one can fertilize even heavier than the "production" dose of 1 teaspoon per gallon. I've gone as high as a Tablespoon per gallon, but I obviously won't recommend that to others. Anecdotally, it didn't do any harm...but seemed to correlate with an exceptionally quick recuperation of my yellowing citrus.

Josh