The ASIC flows are nearly the same. The only differences are that the tools are customized to suit a particular IC Fabrication house such as TSMC, AMI or their own fab house. These COTs may be more suited for Full-custom IC design with complete sets of built-in standard cell libraries (more than what is available in the other tools such as Cadence, Mentor,etc). COTs may also have their own synthesis, layout and P&R techniques that may be better suited for the company.