event loop vs threads

[srinivas devaki]

how does Python switch execution and maintain context i.e function stack
etc,.. for co-routines and why is it less costly than switching threads
which almost do the same, and both are handled by Python Interpreter
itself(event loop for co-routines and GIL scheduling for threading), so
where does the extra overhead for threads come from ?

-- 
Regards
Srinivas Devaki
Junior (3rd yr) student at Indian School of Mines,(IIT Dhanbad)
Computer Science and Engineering Department
ph: +91 9491 383 249
telegram_id: @eightnoteight