Almost all EIFS types are built around a rigid foam insulation board, but there’s one recognized exception in the classification.
The foam-based types
The core EIFS family — Polymer-Based/Barrier (PB-EIFS), Moisture Drainage EIFS (MD-EIFS), Polymer-Modified (PM-EIFS), and Polyisocyanurate (PI-EIFS) — all consist of a substrate, EPS/XPS/polyiso foam board attached adhesively or mechanically, a reinforced base coat, and an acrylic finish coat (InterNACHI, InterNACHI course material, Wikipedia). The color of the foam is actually a decent field clue you already know well: white often indicates EPS, tan can indicate PI, and blue/green/pink usually indicates XPS.wikipedia+2
The exception: DEFS/DA
Direct-Applied Exterior Finish System (DEFS, also called DA) is applied directly to an approved rigid substrate like cement board or DensGlass — no insulation board at all — yet InterNACHI’s standards still list it under the EIFS family classification (InterNACHI course material, InterNACHI Phase I Standards). So technically, within InterNACHI’s grouping, DEFS is an EIFS-family system that is not applied over foam.nachi+1
Outside the EIFS classification entirely
It’s worth distinguishing this from synthetic stucco variants that are explicitly excluded from the EIFS definition even if foam happens to be present, per ASTM/IBC: traditional hard-coat (3-coat) stucco or one-coat synthetic stucco can be applied over a foam board for insulation, but because they lack the polymer base-coat/mesh/finish lamina structure that defines EIFS, they’re classified as stucco with insulation, not EIFS — foam presence alone doesn’t make a cladding “EIFS” (Wikipedia, Walls & Ceilings). Conversely, per Canadian Stucco, EIFS-type coatings can sometimes be applied without insulation directly onto hard sheathing, producing a solid “tap test” sound similar to true stucco rather than the hollow sound typical of foam-backed EIFS.wikipedia+2
So for field identification purposes: if it sounds hollow when tapped, it’s almost certainly foam-backed EIFS; if it sounds solid, it could be either traditional stucco or DEFS without foam — you’d need to check for the base-coat/mesh/finish lamina to confirm it’s DEFS.