Question

how are DNA and mRNA different

Answer 1

mRNA= messenger RNA, which is used to make DNA in the process of translation

Answer 2

sunshao1, I hate to say it but that's partially incorrect

Answer 3

DNA is the stable template stored inside the nucleus of every cell. From it, DNA dependent RNA polymerases (or just RNA polymerase) comes in and transcribes the DNA message into mRNA (messenger RNA). The messenger RNA is transported outside of the nucleus and undergoes post-transcriptional modification where a 5' cap and a 3' tail are added by the polyadenylation polymerase enzyme complex between the golgi and the cytosol.

Afterwards the processed mRNA is usually captured by a complex of promoter proteins that recruit a Ribosome to the mRNA strand. Here a the ribosome uses the mRNA as a template to construct a brand new protein (polypeptide chain) that can go around the cell and serve useful functions.

tl:dr
DNA is stable, stored in the nucleus, double stranded, and has only one OH group on the ribose sugar.

mRNA is unstable (with two OH groups on the ribose sugar), usually single stranded, is transported outside of the nucleus, and is designed to be translated into proteins.

Answer 4

Addendum:
It should also be noted that mRNA is more prone to have errors in it because the RNA polymerase does not have 3' to 5' exonuclease proof reading activity.