variant; successor model; developed form
Used for an evolved version, derivative, or next-generation model of something, often in technical, product, or conceptual contexts.
A successor model of this software is scheduled for release next year.
A new hypothesis was proposed as a developed form of that theory.
改良型 highlights improvement or refinement, whereas 発展型 can imply a more substantial transformation or next-generation version.
Compound of 発展 (development, evolution) and 型 (type, model). The exact historical derivation is uncertain, but the word follows a common pattern for naming evolved or successor forms.