Well the ADV tag is used on a certain type of games usually this tag is used on wrong games because nobody knows what is the meaning or for what is used usually foreign users so i will make really clear the differences betwen this and the games which is used
This tag has been used wrongly on visual novels,is not wrong in some cases and because of this is wrongly used because the ADV and VN use the same engine in most cases
Visual Novel - Tag VN : Usually the visual novels have only story in rare cases with one or two selection in the entire game and those selection are made at the end due to the autor making those selection for good end and bad end this is the reason most people get confused,this type of game is straightforward and mostly story.
Adventure Visual - Tag ADV : This is the type you are talking,this type of games is a mixture betwen visual novel and other types of games,in some cases it has elements of RPG like Arcana Avatar Akari but mostly this type of games have hundred of answer selection and lots of ends depending on your answers and lots of CG ,this type of games is one of the most popullar because of the choices and is not straightforward so your choices change the ending and the route of the game wich has cross route in the middle which can change the ending so you can have 2 times the same ending but taking different routes.
And example of ADV
.- Custom Raid V
.- Kodomo Milk Parfait
.- Arcana Avatar Akari
.- Shoujo Ramune
.- Urawaza Spectrum
Those are the most common representation of Adventure Visual or ADV.
I could mention visual novels but i havent buyed any.
Also something i forgot to mention the visual novel and ADV have voices but in the case of the protagonist the ADV has not voice for the protagonist whatsoever because in the ADV you are the protagonist,and in visual novels the protagonist has voice but not the narrator wich is you.
So if you find a game tagged like visual novel but has lots of answer options then is an ADV