The only difference between all 1, 2, 3, 4 kata is the block: in dai ich dosa or no.1, the basic uke is yoko uke (middle outward block), and no. 2, the yoko uke together with mae geri (front kick) no.3, gedan barai (lower strike a.k.a hara uke or lower stomach block) and lastly no. 4, the block is age uke (upper block).
And for the kihon kata (neko ashi dachi) or cat stance version, I guess u know what is the different with the earlier one:-) Of course! the stance! and also for no. 3, extra yoko uke must be added before gedan barai and no.4, extra yoko uke also must be executed before we do age uke.
I have not reach to my point yet, i.e. actually, the significance is not only to ensure the beginners undertand, appreciate and familiarize with these basic techniques or waza, but actually it has a very important relation with later series of Heian Kata that they need to learn in later kyus, i.e. yellow and above...
So, wait for next article that i love to share!!!
Hope u have gained something from here...
Till then. matta ai masho:-)