Kriyas Megilla and Kriyas hatorah

From the mishna on todays daf that switch's gear from kriyas megilla to kriyas hatorah it became clear to me in a new way the relationship between the two. The gemorah on daf 14a says that the only thing that the neviyim added on to the torah is kriyas hamegilla. The gemorah says that the hosafa is not the yom tov of purim, not the writing of the megilla but the reading of the megilla. What chazal added on to the torah was a new kirya that is begader kriyas hatorah, as we have seen that the megilla in its kisva has dini sefer torah, sirtut, tefirah bigidin ect. Chazal instituted a kirya similar to kiryas hatorah but with some differences, for example the kirya of the megilla is medin shira mah sheain ken kriyas hatorah is not midin shira. this chiluk creates a halichik difference that you can have tri koli by megilla.( maybe this chiluk can help answer Yossis' earlier post) Also the days that chazal insituted for the kirya of kefarim is monady and thursday the same days that we read the torah. and the rambam when he talks about hilchos megilla it is all focused on dini keriya till the very end when he talks about mitzvos hayom.