Determinates have short vines, Usually two to three feet in lenght.
They make up for the lack of fruiting space by growing side shoots (
what you are calling suckers) which will approach the lenght of the
main leader, giving the plant a bushy look. Each of these side shoots
bear tomatoes approaching the rate of the main leader. If you cut them
off you only get tomatoes off the main leader. It is not as critical
with an indeterminate as the main leader keeps on going and setting
fruits further up the vine. Some of them when trimmed to a single vine
will reach 25 feet in lenght. One of the reasons determinates are the
choice of commercial growers is that that they give you a tremendous
yield over a short period of time. The side shoots are what makes it
possible.