Previously, Small Scale Industries (SSI) were the small business entities that were registered under the Ministry of Micro, Small and Medium Enterprises (MSME).
However, since July 2015, SSI registration was replaced by MSME registration.
Udyog Aadhaar is a 12-digit unique number provided to MSMEs for registration purposes.
In short, MSME and SSI registration are the same, and Udyog Aadhaar is the registration process for MSMEs.
