Winter and summer bees differ significantly in how long they live; 4-10 weeks (usually 6) for summer bees and up to 7 months for winter bees *.
What I didn’t know is that this is predestined from their time as a pupa (I had thought they just changed as an adult based on conditions). Apparently the temperature of the brood nest defines their physiology. Bees raised at 36°C will be summer bees, but raising them at 34.5°C will result in winter bees.
Cite : BBKA No223, pg381. HOBOS.
* winter bees are also noted for growing ‘fat bodies’ which allow them to store energy for longer periods which helps them get through the cold of winter.