Ranks are not official among most non-coven witches.
Also, they can depend on the topic. For example, one can be advanced in green witchcraft, but a beginner when it comes to spiritwork.
When one transitions from one level to the other is completely subjective; one person may feel they are a novice lunar witch after spending one year studying, another might feel you're only a novice after performing a certain amount of spells.
Those are more just fun little colloquialisms people use for themselves to have a little fun.
Baby witch- new to the proverbial world.
In the broom-closet- a witch in hiding/who feels they need to conceal their practice from their closer circles of relationships. (Family and friends)
The other 'rankings', like beginner, novice, learner, expert, etc. are all dependant on the circles you travel (pun intended) and their individual criteria. If they even use those terms. Some might use older or more exotic titles for a more mystical flair.
Well, this site has a ranking system, but so few people can rank members it's more of a guideline than something you receive after a test or something similar. The ranks are fluff or no rank, beginner, novice, knowledgable and adept.
As for ranks outside of the site, as mentioned, it depends on the path. If you're in an initiatory system, they might have milestones and knowledge checks you must pass before being permitted to study more advanced work, but it's not universal. You're always learning in the craft. Outside of the site, I don't have a rank [I've never had a rank] and I've been practicing for almost 17 years. And despite being a witch for over half my life, I'm no expert in every aspect of witchcraft. I could easily help you with things like dream interpretation, working with spirits and deities [especially Egyptian deities] but if you come to me with a crystal or rune related problem, I'll probably look at you the same way a dog reacts to a high pitched noise. You're always learning and growing on this path. The only time a rank matters is if they're a teacher [and even then they could lie]
My advice is a line from an old song; "Be careful whose advice you buy, but be patient with those who supply it." Someone can offer great advice, but if it doesn't resonate, don't use it. [and if they boast about being a level 16 warlock with ancestors from Salem, that's a scam, walk away]