What does VCarve Desktop lack compared to VCarve Pro, and is the 24″×24″ limit per sheet or per project?

The headline difference: job size

VCarve Desktop supports job sizes up to 24″ × 24″; Pro is unlimited. The limit is on the job size, and the official pages do not spell out whether it is counted per sheet or per project, so check this in the free trial if it matters for a multi-sheet job. Parts larger than 24″ × 24″ can still be cut on Desktop by using Toolpath Tiling, which divides the toolpaths into sections you cut one at a time. Only Pro and Aspire can cut larger parts in one piece without tiling.

Everything else Desktop LACKS vs Pro

Per the official comparison page, Desktop does not have:

• Gadgets: none run on Desktop. That's why the Gadgets menu is missing or empty, and it's an edition limit, not an install problem
• True shape nesting (Nest Parts)
• Toolpath merging and toolpath/job templates
• VCarve Inlay toolpaths
• Array Copy toolpath
• Job Setup Sheets
• Keep-out zones
• Advanced Machining Module support (the official FAQ lists support in version 12.508 or later of Aspire, VCarve Pro and Cut2D Pro)

What Desktop DOES share with Pro

The 2D design suite, V-carving, Photo V-Carve, profile/pocket/drilling, two-sided machining, 3D clipart assembly and machining plus one third-party 3D model, and rotary machining: the 12.5 Desktop documentation includes Job Setup and Material Setup for rotary jobs and describes wrapping toolpaths around a rotary axis. The Laser Module is an add-on for every edition.

Buying advice

Desktop suits benchtop machines (about a 24″ envelope) doing signs and flat work. If your machine bed exceeds 24″, or you'll batch parts with nesting, templates and gadgets, buy Pro. The upgrade later costs the price difference anyway.