As the title says.

I have base Witcher 3 and I just bought the 2 dlcs.

I now also have the GOTY version but is there a difference or can I just ignore it?

There is no difference. It's just a single installer.

In GOTY version main menu switches randomly between three themes (from basic game, HoS and BaW), in version 1.31 non-GOTY (with two add-ons installed) menu always uses theme from Blood and Wine. Content-wise, the game is the same in all versions.

Saves are compatible between these versions, but mods are not.

I wanted to ask this question too. Nice. No need install GOTY, but nice that it is in library,

What about this?:

-Features all technical and visual updates as well as a new user interface completely redesigned on the basis of feedback from members of the Witcher Community.

Visual update, do they mean better graphics texture improvment etc?

UI and inventory screen were redesigned in one of the patches (I believe it was patch 1.21), so this description may be a bit misleading. GOTY has no exclusive interface or graphic enhancements. I think we can understand the term "visual updates" as minor tweaks made in all previous patches, but it's definitely nothing new created specifically for GOTY release. With GOTY version you get the same textures, models, graphic options, music, interface as in the patched non-GOTY version.

Thanks for the info. I won't bother reinstalling then :)

I notice the GOTY version is alot smaller in size to download, compared to W3 and all the dlc downloads ? why is that, also, does the GOTY version also come with the free 16 dlc included ? thx

GOTY includes all 16 DLCs and 2 big add-ons. However, enabling/disabling alternative outfits and other stuff from free DLCs in GOTY is listed in game options under "Gameplay", not "DLC" as it was in non-GOTY version. W3 GOTY is the definitive edition of The Witcher 3: it has everything and lacks nothing from base game nor add-ons. No need to worry.
Different download size may be the effect of another type of used compression or something like that.