Answer:
The conditions for the steerage/third class were very poor compared to the first class. Since first class usually has quite wealthy families and people, they had a much better and luxurious amenities and accommodation. Third class was quite cramped, with much less space to sleep in, and do anything in, also the amenities were much less luxurious than that of the first class.
This is the best I got as there wasn't any diagram or specific text to cite from (there weren't any attachments for them).
I hope I helped.
