Is there a huge difference bewteen Saline implants 400cc High Profile and 420cc Moderate profile?

Thank you for the question. Generally speaking, women considering breast augmentation surgery should understand that it is really not helpful for them to compare themselves to other women, even if they have the same height/preoperative measurements/appearance.  There are many variables that go into selecting the appropriate breast implants for a specific patient (who has unique anatomy and very personal goals). In regards to specific size/profile of breast implant, despite good intentions, online consultants will not be able to provide you with  meaningful specific advice.  Ultimately, in person consultation with well experienced board-certified plastic surgeons will be necessary. Careful measurements, dimensional planning, and careful communication will be key.
Generally speaking, the best online advice I can give to ladies who are considering  breast augmentation surgery ( regarding breast implant size/profile selection) 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're looking for. Ask to see lots of examples of his/her work.
2.  Again, have a full discussion and communication regarding your desired goals with your plastic surgeon. This communication will be critical in determining which operation and/or 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 "C or D cup" 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.  The use of computer imaging may be very helpful during this communication phase.
3.  Once you feel you have communicated your goals clearly,  allow your plastic surgeon to use his/her years of experience/judgment to choose the breast implant size/profile that will best meet your goals.  Again, in my practice, this decision is usually made during surgery.  The use of temporary intraoperative sizers with the patient in the upright position are very helpful. I hope this, and the attached link, helps.

I am not surprised that a patient with high profile implant looked large as these implants project more.  The moderate profile plus as a much more natural looking breast implant.  However if you are concerned about going to Baig you should revisit your plastic surgeon for a breast implant sizing system evaluation during which implants a various sizes can be placed into a non-padded bra and you can see how you will look.For more information on choosing breast implant size please read the following link:

You did not post a photo so very hard to advise. Best to see your surgeon again to fully discuss the some to be used until you are completely satisfied...