Difference between python thread vs gevent greenlet

gevent_thread_demo.py

#!/usr/bin/python

# Output is NOT interleaved

import gevent

def print_numbers(name):
   count = 0
   while count < 500:
      count += 1
      print("Thread: {}, count: {}".format(name, count))

g1 = gevent.spawn(print_numbers, "Thread1")
g2 = gevent.spawn(print_numbers, "Thread2")

gevent.joinall([g1, g2])

python_thread_demo.py

#!/usr/bin/python

# Output will be interleaved with Thread-1 and Thread-2

import thread

def print_numbers(name):
   count = 0
   while count < 500:
      count += 1
      print("Thread: {}, count: {}".format(name, count))

thread.start_new_thread(print_numbers, ("Thread-1",))
thread.start_new_thread(print_numbers, ("Thread-2",))

while 1:
   pass