Check the ballast for recommended wattages.

The lights are actually working fine. They take awhile to warm up and then the rippling stops. Now they are not quite as bright as the GE 40 watt bulbs but they are ok. The sylvania is 34 watt and supposedy more efficent, it just doesnt seem as bright as the 40 watt bulb. Again I dont see anywhere on the balllast where it says what type of bulb to use. I bought the fixtures used on craigslist and they already had some older 40 watt lights in them. My main question was are T8 and T12 lights completly different, as in different size bulbs.

Yes the bulbs are different in width. T8s are approx 1". T12 are approx 1 3/8".
As stated above "Check the ballast for recommended wattages". They may only be 32w. T8s usually put out more lumens per watt. The ballast is inside the fixture.
BTW you need as much light as you can get, get rid of the 34w bulbs no matter the actual wattage. Use them in the kitchen or the garage but not on plants.