Different varieties will grow at different rates and with different vigour.

As for the container difference - are we talking paper, plastic or foam? Dixie makes all 3. Paper wicks water away, foam insulate the soil temps somewhat.

As a general rule, cups will not drain as effectively as pots made for the purpose. That means slower root development and less top growth. Holes you make in cups need to be as similar as possible in size and location to those on the pots. The shape of the cups with their narrower bottom can also have a minor effect.

Bottom line - cups can work but are not as good as purpose-made pots.

From your photo your plants are very over-crowded. Over-crowding causes leggy, stressed plants. If there are still 8-10 plants in each of those pots they need to be separated ASAP.

Dave

Thank you -- makes sense. Just potted up all the taller tomatoes today. The Dixies (paper) are next. Using Craig Lehoullier's dense planting method. He crams up to 30 seeds per cell using a 50-cell tray and pots them up after about a month.

Yeah I am familiar with Craig's method and use something similar myself. But that is just for germination and initial growth and they are then quickly transplanted into separate containers.

Dave