RKMBs Forums .::Robegories::. Media Star Trek: The Lost Generation

I'm not into the original series, G Man.... but I do have a question :

Why, in " Q Who" , when Q threw the ship 7,000 light years away from the Alpha Quadrant, was it said that it would take 2.5 years at high warp to return home....

While, in Voyager, Janeway says in the first episode :

" It will take just over 70 years to travel the 75,000 light years back to Earth."