Both are testosterone esters that are oil soluble. The oil is slowly absorbed and the T+esters when free molecules have the ester groups removed. The net effect is a time release bio-identical T delivery system. So all you are getting is testosterone, no difference.
T cyp and eth are mostly the same. Eth is processed a bit faster than cyp and yields a bit more T. So the two are interchangeable and your concern might be better off focused on cost and availability. The two have typically be in different oil bases, but the oils used are now much more variable than in the past.
You need to be careful about what you read on body building sites. The doses are very high and the potency is probably off too. The side are dose related and not a factor of what ester is used.
Your TRT dose should be near 100mg/week. Your sides may be dose related.
Your sore nipple is from elevated E2 and you need to manage E2 with anastrozole.
Your testes will probably be getting smaller and fertility can be at risk.
Please list your total protocol and other details [including time-line].
What are your goals/objectives?
You need lab work: -bare minimum
Please read the stickies found here: https://forums.t-nation.com/t/about-the-t-replacement-category/38/2?u=ksman
- advice for new guys - need more info about you
- things that damage your hormones
- protocol for injections
- finding a TRT doc
Evaluate your overall thyroid function by checking oral body temperatures as per the thyroid basics sticky. Thyroid hormone fT3 is what gets the job done and it regulates mitochondrial activity, the source of ATP which is the universal currency of cellular energy. This is part of the body's temperature control loop. This can get messed up if you are iodine deficient. In many countries, you need to be using iodized salt. Other countries add iodine to dairy or bread.