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.

This is a common question and can not be answered without an exam or photos.   A high profile implant will give you more projection and roundness.  Discuss your concerns with your plastic surgeon.  

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... 

There is no way to answer your question based on the cc's of volume of an implant. Like fitting your foot in a shoe or your body in a dress, it does not mean much to compare shoe or dress sizes and how they will look on you compared to another woman even if she seems about the same height/weight. Implants are like pillows behind your breast and must be properly sized for your breast and then what effect they will have from the forward volume (profile). The last thing to note is the number of cc's. If the saline-filled implants you are talking about are both from the Mentor company, they are not properly scaled for the width/diameter of the implant. Allergan's high profile saline-filled implant is properly scaled for the width/diameter of the medium profile.You need an implant that has a diameter that is about 3/4 to 1 cm less than the width of your breast upright and with arms down. It will then fit, properly fill out the base of your breast, and look natural (round, smooth surface implants, under the pectoralis muscle). If that implant has a medium profile, you can expect to look about 1 1/2 cup sizes larger than you do now. If it's a high profile implant of the same diameter, then you can expect to look about two cup sizes larger than you are now. Other women's breasts and choices don't enter into it and the effect of the number of cc's is different for different women with different breasts. 

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: