Most reformer studios publish a level system — 1, 1.5, 2, 2.5 — and it is a genuine attempt to solve a real problem. It half works. A number tells a newcomer how difficult a class is, and leaves them to guess whether that difficulty is for them.
What actually decides where you should start is not difficulty. It is whether you know the machine, what your body is currently doing, and what you want. So we ask those three things directly and name a class, rather than publishing a number and hoping you can do the translation yourself.
The spring load in every class is yours to set. Two people on adjacent reformers doing the same exercise are frequently doing quite different amounts of work, and no instructor here reads that as a ranking.