The Treasury Board manages the government's financial, personnel, and administrative responsibilities. Considered the general manager and employer of the public service, it sets policy in these areas, examines and approves the proposed spending plans of government departments, and reviews the development of approved programs.
http://www.tbs-sct.gc.ca/common/us-nous_e.asp#TB
Finance Canada plans and prepares the federal government’s budget, we analyze and design tax policies, and we develop rules and regulations for Canada’s banks and other financial institutions.
We administer the transfer of federal funds to the provinces and territories.
We develop policies on international finance and help design our country’s tariff policies.
We also monitor economic and financial developments in Canada and provide policy advice on a wide range of economic issues.
In short, we help manage the nation’s bank account and we provide advice to the Government with the goal of creating a healthy economy for all Canadians.
But there’s a lot more. Explore this site to find out how much more.
http://www.fin.gc.ca/fin-eng.html
To put in plain english, Finance Canada is @ macro level, as Treasury Board Secretariat is @ micro level.