The Types dimension of HEFA SAF market taxonomy differentiates feedstock origins and processing pathways, each influencing cost structure and lifecycle emissions. Vegetable‑oil‑derived HEFA (e.g., soybean, rapeseed) remains the largest subtype, benefitting from established agronomic supply chains and relatively predictable yields, thereby supporting the bulk of commercial blending ratios. Animal‑fat‑derived HEFA (tallow, poultry fat) offers a higher carbon‑intensity reduction potential due to its waste‑stream nature, yet faces logistical constraints linked to collection and rendering facilities. Waste‑cooking‑oil HEFA leverages municipal and industrial waste streams, delivering the steepest GHG abatement per barrel but requiring robust feedstock certification to mitigate contaminants. Finally, Algae‑based HEFA is an emerging niche, characterized by rapid growth cycles and the prospect of decoupling fuel production from arable land use, though current commercial scale remains limited. Each subtype contributes to the overall market size by expanding the feedstock base, diversifying risk, and enabling differentiated pricing strategies across the supply chain.