Digi ESP: What is the difference between src.py and dpdsrv.py ?

Dear
what is the difference between execute directly the source:
python xxx.py

and execute :
python dpdsrv.py

ie


import sys, os 

sys.path.insert(0, os.path.join(os.path.abspath('.'), '_xxx.zip'))

print "Launching Python application '%s' ...
" %'xxx.py'

if not os.path.isdir('/Users/prolland/workspace/xxx/src'):
    execfile(os.path.join(os.path.abspath('.'), 'xxx.py'))
else:
    execfile('/Users/prolland/workspace/xxx/src/xxx.py')

best regards.