The major difference between Business Visa and Startup Visa is that the Startup Visa (even though it is called a 'Visa') is the Permanent Residency in Canada path. However, the Business Visa is a temporary visa for businessmen to come to Canada for an extended period of time to build a new business or operate an existing one. Business Visa comes with the proper Canadian Work Permit issuance with the business that the candidate intends to operate as an employer.
Startup Visa has an incorporated opportunity to come to Canada before (!) the Permanent Resident of Canada status is granted, and that is also a Work Permit – that is the only similarity of these two programs.
Overall, both programs are complex but very useful and lucrative for business-people. Therefore, consultation is highly recommended to select a proper path.