hell911 said:
What are the Disadvantages of changing institution?
in all aspects, travel, society, cost, etc.
im thinking to move from centennial to seneca, but not 100% yet.
So you still seem to have plenty of worries in mind. To attend to your query, one can change the college, institute or university as long as it follows the following;
http://www.cic.gc.ca/english/helpcentre/answer.asp?q=487&t=15
I want to change my school or program of study. How can I change my study permit?
Primary school student
You must apply to modify your study permit when you move on to high school. Send your application to the CIC Case Processing Centre in Vegreville, Alberta.
High school student
You must apply to modify your study permit when you move on to post-secondary school. Send your application to the CIC Case Processing Centre in Vegreville, Alberta.
Post-secondary student
You may change your school, program and/or field of study without applying for a new study permit. You do not need to apply for a change to the condition of your study permit, either. You may continue to use your study permit as long as it is valid.
If you are changing your level of study (e.g., bachelor’s to master’s), you do not need to apply for a change to the condition of your study permit, either.
Now, Centennial and Seneca or for that matter, GBC HUMBER etc aren't far from each other and fall in the same province. It doesn't even impact the cost factor as well much or job prospects. About college fee, it's standard across all public colleges which is usually around 13,500 CAD for international students a year. But yes think about before switching, will you get credit transfer, will there be a fee you got to bear for transfer etc.
Seneca is a much better choice over Centennial (personal opinion, so anybody not comfortable with this part of my reply, refrain from contradicting, it's a personal opinion).
Cheers!