Sorry in advance for being pedantic.
"Epigenetics" refers to heritable modifications that affect gene expression. Epigenenic modifications call also be made to proteins and other cell components (some of the best characterized are histone modifications). DNA base modification, by itself, is not necessarily 'epigenetics' because not all modifications persist to the next generation or even through the next cell division. So, some DNA base modifications are epigenetic while others aren't and it's hard to tell which is the case without tracking the changes over time.
And really, epigenetics has largely turned into a buzzword or marketing term for grants in research to try to differentiate the study of the underlying mechanics from other, previously identified regulatory mechanisms. Kinda like how the suffix 'omics' gets added to research field names. At the core, epigenetics includes a number of interesting mechanisms within the larger context of biological regulation.
