The duration of the work permit would depend upon the length of time stipulated on the contract. When you applied at Seattle, it was your initial work permit and for Live in Care givers they give 4 years because that's how long you should finish your program and be able to apply for permanent residency.
my friend apply at brorder but they only gave her 2 years of worjer permit. I applied in Seattle whenI have US visa then they gave me four years of WP. I wonder if I renew my WP at brorder, do they will shorten my WP deadline? If they do, I would rather apply online inside Canada. right!