Answer to Question #60552 in Genetics for Sanjukta Ghosh
(It has something to do with single stranded state and double stranded state, isn't it?)
mRNA is a coding RNA, while the rest are small, non-coding RNAs.
piRNA is Piwi-interacting RNA.
piRNAs are primarily there for maintaining genomic integrity by stopping transposable elements.
All of them interact with the Argonaute family of proteins, but piRNAs interact with the PIWI subfamily, while miRNA interact with the AGO subfamily. This means that they have different places where they act, with piRNAs restricted to the germline, while the others are fairly widespread physiologically.
I had asked about the difference between miRNA and piRNA. The answer is about mRNA and piRNA.