There is hardly any difference to choose in either of two forms, as both would work in same way. Except, that injectable, start work in a day while oral form may 3-5 days. But as a physician, nobody would advice you to take them. They may be helpful in shaping your body and give you some good early looks, in long term they can be harmful. The side effects and adverse effects are many and affect whole of the metabolism. Without steroids, one can achieve better muscle mass (although that take some more time), but it does not have any affections to our body's normal physiological mechanisms.
Hope this helps.
Please feel free for your follow up questions.
The body has a high physiological reserves and majority would recover completely in month or two use. But anything which is deleterious for health, medical advice is; not to use them. Although an individual choice is to be respected. Just a caution; a small fraction of people may cause liver and other minor metabolic problems even with short term use.
It is pleasure assisting you.