In LSL, functions like llGetTexture() return either a texture name or its UUID, both as strings, and string–key comparisons work.
In SLua, string and uuid are distinct types. For instance, in an object with blank textures:
print( ll.GetTexture(0) == TEXTURE_BLANK ) -- > false
We must cast to uuid:
print( uuid( ll.GetTexture(0) ) == TEXTURE_BLANK ) -- > true