Originally at the beginning of the well-balanced program rules to go with the new judging system,
Senior ladies LP included 4 spins, 1 step sequence, and 1 spiral sequence
Junior ladies LP included 3 spins, 1 step sequence, and 1 spiral sequence
So at that time, the difference between the two programs was that seniors had an extra spin.
Both junior and senior ladies got 7 jumping passes. That is still the case.
Two years ago, it was decided to delete one element from the long programs to allow more time for choreography.
The deletions were the fourth spin from seniors and the spiral sequence from juniors. So now the nonjump elements are
Senior ladies: 3 spins, 1 step sequence, 1 spiral sequence
Junior ladies: 3 spins, 1 step sequence
The difference is a spiral sequence.