I dont know alot about windows but imo the biggest diference is Active Directory,since every company uses AD I think its critical to know it well if youre gonna do internal pentests(there is a retired box for that to practice once you learn it).There is a course for that on hackthebox academy also.Apart from that I think a bit of powershell may be good to know.To practice hacking windows I really recommend VIP as there’s alot of boxes to choose from.Also forgot to mention windows registry aswell.