The biggest difference between the two, 

is one you feel

and the other 

you do

Lonely is a feeling 

comfortable to the sad

loneliness will send you reeling

with thoughts truly bad

Alone is a choice

you take time to yourself

by yourself

it gives time to quiet the mind

and listen to your own voice

Lonely is a feeling

the future looks dark

silence smothers you, 

and loneliness makes it's mark

Alone is a choice,

where heart, mind, and body

rejuvenate 

while the soul will rejoice