Both are located in the Sierra Nevada (California) at the latitude of Fresno. The altitude is about 2000 meters for the Sequoia and goes down to about 1000 meters for the King Canyon.
In the Sequoia Park, you can drive and see interesting view points and hike as there are several trails. Do not expect large views because the park is covered by trees. Of course the most interesting trees are the sequoias, of which the "Sherman Tree" is the largest tree in the world ! The "Grant Tree" (on the road to the King Canyon) is just a little bit smaller. The road in the park is rather slow and there are not so many parkings.
The King Canyon park has a "V" shape ; there are not so many trees in this park but the views are spectacular. The road goes down from the Sequoia park and follow afterwards the river at the bottom ; you return by the same road. You find also trails especially at the end of the road. When I was there (October 2012) the Sequoia Park was in the clouds but descending to the King Canyon lets the sun appear.

Count one day to visit each park.

This road was only big enough for one and a half cars at most. Plus there were a lot of blind spots, and no guardrail of any kind. One mistake and that's it....your history...I prayed all the way up and down everytime I had to drive it.

The brochure I read states that this road has 698 tight turns. I think it is correct. The road ends in a valley surrounded by mountains. There are plenty of hikes that go up to gorgeous mountain lakes & waterfalls. A few miles before the end of the road is Silver City, where you can grab a bite to eat.

Love the hike at White Chief but if you are out of shape, DO NOT attempt the hike. Make sure you are acclimated to the altitude for a night or two before hiking so you don't get altitude sickness (nausea, vomiting => brain swelling). Take your time and enjoy. Marmots may chew on your radiator hose so park your car a mile down the road from the hike and hoof it up. If not, get chicken wires and wrap it around your car. Don't let these cute friendly creatures deter you from hiking this Swiss Alps look alike beauty.