Juan D’Arienzo recorded El Choclo four times, in 1937, 1948, 1954, and 1963. I think just maybe he liked it! The recording syncd. below is the 1954 version. He does a lot that is not on the page. That’s an understatement! But the basis is very much the piano sheet music. I find it very instructive to follow the score and listen carefully to how D’Arienzo elaborates it. His playing is multi-layered. Not just in El Choclo, most of the time. That is a big part of his style. That and the consistent marking of the “4” count, and of course those punchy rhythmic accents.
The D’Arienzo’s plays the s is A-B-C-B-A. In music theory such an ordering is called arch form. A few different (more than two) sections are played consecutively (A-B-C in this case) then in reverse order (B-A). Hence an arch: a symmetrical rising then falling back. Composers/arrangers make a very conscious decision regarding form because the ordering of sections greatly effects the overall character and musical qualities we experience when listening (and dancing) to the music. Each of the El Choclo syncs I have provided use a different form. I recommend carefully listening to each one and hear for yourself how form influences the listening/dancing experience.
Composers/arrangers make a very conscious decision regarding form. The order sections are heard greatly effects our sensations and responses as listeners and dancers.
Sections are the top level element of music's form. They are the the large building blocks of tango music, typically lasting around thirty seconds or so. Each section is a unique segment of music, having a distinct musical character.
Tango music has two, occasionally three, primary sections, which we may label “A”, “B”, “C”. Sometimes there is an "Introduction", "Bridge", a short section between two larger ones, or "Coda", a short concluding section.
Usually each section will be played consecutively in order (A then B then C), followed by various other orderings. Typically in tango songs each section is played instrumentally then each is sung, then section A is played instrumentally: A-B-A (vocal)-B (vocal)-A. But there are many exceptions and other possibilities.
Phrases exist within a section.