First, what is Transcriptome:
The transcriptome is the set of all RNA molecules in one cell or a population of cells. It is sometimes used to refer to all RNAs, or just mRNA, depending on the particular experiment.
And what is Epitranscriptome:
Within the field of molecular biology, the epitranscriptome includes all the biochemical modifications of the RNA (the transcriptome) within a cell. In analogy to epigenetics that describes “functionally relevant changes to the genome that do not involve a change in the nucleotide sequence”, epitranscriptomics involves all functionally relevant changes to the transcriptome that do not involve a change in the ribonucleotide sequence. Thus, the epitranscriptome can be defined as the ensemble of such functionally relevant changes.
A wonderful article:
The birth of the Epitranscriptome: deciphering the function of RNA modifications
