Vanilla's water and lava tags include the flowing state of the fluid, not just the source. Embers doesn't.
Could be a design decision of course, but if someone were to build something that triggered based on presence of a certain fluid, only the source blocks would trigger it, which seems undesired, especially with the fact most of the fluids are added to Forge tags and not specifically Embers tags.
Vanilla's water and lava tags include the flowing state of the fluid, not just the source. Embers doesn't. Could be a design decision of course, but if someone were to build something that triggered based on presence of a certain fluid, only the source blocks would trigger it, which seems undesired, especially with the fact most of the fluids are added to Forge tags and not specifically Embers tags.