I am working in RNA seq analysis and I am going to use the gene model (annotation file .gtf) for human (hg19). I found different releases for that like GRCh37.55, GRCh37.61, ...........GRCh37.75,.........
When I looked inside each release, I found that the order of chromosome on them not the same (i.e some start with chr1 then chr 10, chr11, chr12, ......, and chrY. and other one start with GL000213.1, then HSCHR21_2_CTG1_1, then chr18,..chr 10)
My question is there any difference of use them with the same order on them, and Why/what these differences between them (i.e why they change the chromosome order in each release)