1. Rūpa (form)
2. Vedana (feelings/experienced-sensations)
3. Sañña (perceptions)
4. Saṅ-khārā (co-activities)
5. Viññāṇa (consciousness)

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2.1 – SN ^22.79 definitions don't make the difference clear.

The Agama parallel SA ⁴⁶🔗 uses more standard definitions unlike SN 22.79.

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2.2 – Dr. William Chu translation of relevant passage

(along with some context from earlier Brahman religions)

	"All the perceptions is what the clung-to aggregate of perception about. What are these perceptions? The perception of singularity, the perception of multiplicity, the perception of infinity, and the perception of 'there's no do-er whatsoever and there's not a thing whatsoever.' That is what is meant by the clung-to aggregate of perception."	諸想是想受陰，何所想？少想、多想、無量想、都無所有作無所有想，是故名想受陰.
	"The clung-to aggregate of consciousness is about [the ability to] differentiate-discern characteristics (note: the literal translation of vijnana is to differentiate-know). What is differentiated and discerned? Sights, sounds, smells, tastes, tactile feelings, and mental contents [are differentiated and discerned]. That is what is meant by the clung-to aggregate of consciousness."	別知相是識受陰，何所識？識色，識聲、香、味、觸、法，是故名識受陰。

Now, as for the question about how perception is different from

"differentiation as in by consciousness."

For one thing, the "differentiating" in vijnana/consciousness is,

in ancient Indian Upanishadic usage,

about the bifurcation into and reification of subject-object duality.

To be a conscious being is to experience a

"oneself" that stands in opposition to an environment (world).

In Buddhist usage, an added meaning is often found: the experience

of continuity (therefore consciousness is intimately connected with the retention of memory and karmic continuity).

Here's a way to summarize: Being conscious is being aware of

senses and their corresponding objects; being conscious is also

about experiencing continuity--to have memories and to be able to anticipate the future.

To be a percipient being, on the other hand,

is to experience

"specific contents" such as "there is a multiplicity/diversity

of experience...there's only One-ness...there's not-a-thing."

In Buddhist cosmology, all sentient beings are conscious,

but not all beings are necessarily percipient.

An example would be a human in deep sleep,

an asanna being in the non-percipient state--both are said to be conscious without experiencing specific contents.

A meditator in the nirodha state only experiences the temporary abeyance of feeling and perception,

but is still

"conscious," and therefore retains the continuum/memory of the person when he comes out of the samadhi.

Quite a few Buddhist treatises speak of beings with 5,

4, 3, 2, and 1 aggregates, always with consciousness being the indispensable aggregate.