https://phys.org/news/2018-05-sides-star.html

Some neutron stars, called radio pulsars, have strong magnetic fields and emit radio waves in predictable, reliable pulses. Other neutron stars have even stronger magnetic fields, displaying violent, high-energy outbursts of X-ray and gamma ray light. These are called "magnetars", and their magnetic fields are the strongest known in the universe, a trillion time stronger than that of our sun.

Since the 1970s, scientists have treated pulsars and magnetars as two distinct populations of objects. But in the last decade evidence has emerged that shows they might sometimes be stages in the evolution of a single object. That's right – a neutron star might just be two sides of the same coin – first it's a radio pulsar and later becomes a magnetar. Or maybe it's the other way around.