Vals is probably the most joyful from three tango genres (Tango, Milonga and Vals) with its ¾ happy feel of spinning and floating.
The basic difference is hidden in its rhythm. Vals is written in ¾ notation, which means that one measure consists of 3 quarter notes. Since quarter notes can be divided in many other 8-, 16- 32-, 64-, etc value notes lets leave all this for the musicians and see what it means for us.
In Tango we count each measure as 1-2-3-4, but we only step on 1 and 3.
The Vals is much faster so even though we can distinguish 1-2-3, in the very basic interpretation of Vals we are only stepping on 1 and completely ignore the 2 and 3. How lazy of us….
What happens is that if we are only dancing on 1 and the phrase is still equal to 8 (or multiplications of 8) measures it is fairly easy to dance slow tango to vals music. Everything fits. It just seems slower then usual, but not extremely slow. But even though everything seems to fit somehow the Vals sensation is not there.....