Anatomical to Round implants - will staying with the same cc's look bigger or smaller?

Thank you for your question.There is no accurate/reliable/predictable way to generalize whether the anatomical implants and round implants will give you a certain "look".  Best to specifically communicate your goals.
Ultimately,  careful selection of your plastic surgeon and careful communication of your goals (in my practice I prefer the use of goal pictures, direct examination/communication in front of a full-length mirror, and computer imaging) will be critical. Keep in mind as you are thinking about your goals that sometimes adjustment of the breast implant pockets (capsule adjustments) may be necessary to achieve the outcome you are looking for.
Generally speaking, the best online advice I can give to ladies who are considering revisionary breast augmentation surgery is:
1. Concentrate on choosing your plastic surgeon carefully. Concentrate on appropriate training, certification, and the ability of the plastic surgeon to achieve the results you are looking for. ***Ask to see lots of examples of his/her work.
2. Have a full discussion and communication regarding your desired goals with your plastic surgeon. This communication will be critical in determining breast implant size/type/profile will most likely help achieve your goals. 
In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. I have found that the use of words such as “natural” or "up a cup size”  etc means different things to different people and therefore prove unhelpful.
Also, as you know, cup size varies depending on who makes the bra; therefore, discussing desired cup size may also be inaccurate. 
3. Once you feel you have communicated your goals clearly, allow your chosen plastic surgeon to work with you in determining the best plan to achieve your goals.
I hope this, and the attached link (dedicated to revisionary breast augmentation surgery concerns), helps. Best wishes.

The round implants of the same volume will fit your body and clothes the same. In controlled clinical trials expert plastic surgeons could not discern the difference from anatomical vs round implants. Sounds like you are making a good choice. Good luck....

Generally, when switching from an anatomically shaped implant to around implant of equal volume, with the absence of any capsular contracture, there may be slightly less upper pole fullness than the taller anatomically shaped implant. However, the projection of the round implant may be more.Comparison to a 410 are irrelevant. Overall unless you have very thin overlying tissues, these differences should be subtle. Hope that's helpful.