Last I can address this today. Did a little quick and dirty research.
1. MS-Dos 1.25 - Feature set's not fully implemented no disk space limites, unix like pipes, and others. Although, these features were announced as parts of the OS.
2. Windows 1.0 - MS demoed a over-lapping window system and mult-tasking. V1.0 shipped 1.5 years late with non-overlapping windows and no multitasking. FIrst program to earn the distinction as Vapor ware.
3. MS Dos 5.0 - This is the product that was announced early to compete with DR-Dos.