The short answer
Vinyl and fiberglass are broad frame categories, not uniform products. Compare the exact construction, reinforcement, finish, profile, operation, glass, NFRC rating, maintenance guidance, parts support, and installation scope instead of naming a universal winner.
| Compare | Vinyl | Fiberglass |
|---|---|---|
| Construction | Chambers, insulation, reinforcement | Profiles, composition, finish |
| Evidence | Exact NFRC label | Exact NFRC label |
Sources
Sources
- Window Types and Technologies — U.S. Department of Energy
- What Makes a Product ENERGY STAR — ENERGY STAR
- Window Energy Performance Ratings — National Fenestration Rating Council