There are three:
https://bunpro.jp/grammar_points/261 - 向き
https://bunpro.jp/grammar_points/272 - 向け
and
https://bunpro.jp/grammar_points/327 for に向かって and に向けて
And I just don’t get when to use which because they are almost the same.
Especially the first two.
The third one is at least somewhat understandable because it refers to physical action of facing or turning towards.
No expert here but my 2 cents: I read this as the difference between stem roots for transitive 向ける (むけ) and intransitive 向く (むき). So when I hear むけ, s.o./s.t. is creating the “intention” while intransitive-like むき behaves as ‘just is’…suitable, facing. にむかって and にむけて look to behave the same way; initially 向かう sounds transitive (to face) but really a directional intransitive, otherwise the orange text in the meaning section explains it best.
The orange explanation on the first two seems pretty clear to me.
向き is suitable for, 向け is intended for.
(Also, 向き can be “facing”, which 向け can’t be.)
So a book can be suitable (向き) for children but also for adults (e.g. manga), or it can be made/intended for ( 向け ) children and probably not too interesting for others.
(Drinking) Water is suitable for children ( 向き), but obviously not made for children ( 向け).
You can also say young adult fiction is intended for/aimed at young adults ( 向け), but it’s not necessarily limited to them, because older people also enjoy it.
Of course, these meanings overlap a bit.