Tube acrylics are very thick and are made that way for canvas panting so you can create texture. Folk Art acrylics & Aleene's Premium acrylics are the only bottled paints I've seen that come close to tube acrylics but they are still thinner. Most other acrylic paints have less pigment and are of a very thin consistency.

If you're talking about using tube acrylics for One Stroke painting you will probably have to thin them out a bit to get the right consistency. They are very thick. We're talking like gel toothpaste thick right out of the tube. You have to thin them to different consistencies depending on your project.

The first classes I took in acrylic painting were on wood and we used the tube paints. As Kraftymom said, they just have to be thinned a LOT. Even after I started using the bottles, there were some colors that I still bought in tubes, simply because of the color!