How does a sonatina differ from a full sonata-form movement?

A sonatina is a shorter and often lighter version of a sonata. While a full sonata-form movement typically features a robust development section where thematic material is explored and transformed, the first movement of a sonatina differs primarily in its treatment of this section.12

In a sonatina, the development section is either entirely absent or significantly reduced to a perfunctory role. Despite this omission, the movement still retains the essential structural elements of the sonata form, specifically the exposition and the recapitulation of musical themes.1

This simplified approach is not exclusive to sonatinas; it is also occasionally found in the slow movements of full-fledged 18th-century sonatas and in certain opera overtures, where the demands of overall proportion make the omission of a development section appropriate.13