NFL Preseason Jerseys

[RJB44]

Are the jerseys that players are wearing in preseason going to be the same ones they wear in the season, or will they get all new jerseys/uniforms? I know years ago in baseball, teams wore the previous years jerseys during spring training, not sure how it works nowadays, although it seems that many teams just wear BP jerseys during ST games. This doesn't seem to be the case with football, as players are now all wearing NIKE. Does football always issue brand new jerseys for preseason, or did they reissue jerseys in the past? Maybe this is an exception, because of the off season change in manufacture. Seems like it would be very costly to outfit team with brand new jerseys/uniforms for both preseason and season. I don't collect football memorabilia, so I need a history lesson.

Thanks