Why reformer Pilates can feel harder
A reformer uses springs, a moving carriage, straps, and a footbar. Resistance can be increased or reduced, and the moving carriage can make balance and control more demanding.
Why mat Pilates can feel harder
On the mat, there is no machine helping guide the movement. You often have to support more of your own body weight and create stability using your core, which can make familiar exercises feel surprisingly intense.
Which one is better for beginners?
Either can work for beginners when the class is taught at an appropriate level. A reformer can offer support for some movements, while a beginner mat class can make the fundamentals easier to learn without equipment.
Which one should you choose?
Choose the format you enjoy and can do consistently. If you like equipment, resistance, and variety, reformer Pilates may appeal to you. If you prefer simple equipment-free sessions that can be done almost anywhere, mat Pilates may be the better fit.