Shimano have many series of components corresponding to different grades and categories of bikes (e.g. their high-end series for MTB is XTR while Dura-Ace is for Road), but they also have what they call non-series components which do not bear a series name.
For example, looking at their 2021-2022 line-up chart for SLX, I can see that they list the FH-M7110 (series) and FH-MT510 (non-series) freehubs.
They look similar, but the SLX is significantly more expensive and looks to have a better construction.
Now, are non-series components only meant to be cheaper versions of series components? Why not just include in the line-up chart a compatible component (if available) from lower grade series such as Deore, which is just below SLX? I find it hard to determine the relative quality of non-series components. With series components it is easy, just look at the name.