As I see it, your Segmented Controls are, at their core, the same as Radio Buttons: One item usually selected, perhaps none selected on first load, but after any item is clicked there is always exactly one item selected. A classic Radio Button is quite different from a classic Submit Button (or just "Button"). There are some common alternatives using the same behavior but a different look - e.g., checkboxes where exactly one item can be checked and all others always unchecked. The Segmented Controls are logically the same but fall into the designer's trap of "let's make everything look the same", which is where you are now.
If for design reasons (e.g., mandated by higher-ups) you can't truly change to a distinct "radio button-like" style, then you have a few options:
Size - Make the segmented controls smaller - perhaps 2/3 the height of the separate buttons. That would make it more obvious that they are strips of selections instead of other buttons.
Color - This is often the easiest - but most fought over by designers. So many people go for the "let's use the same colors everywhere" concept, when color can - and should - be useful. On the other hand, if you are designing for an audience that may include color-blind users (and in fact, we all should do that if designing for a large public audience) then color should not be the only method - use size, type of buttons, etc. to make things clear in other ways as well.
Style - Typically something "bolder" for the standalone buttons, or an outline of some sort on the Segmented Controls. But basically something to make it obvious that the control types are different.
Biggest problem with the existing design: What if there is ONLY ONE choice in the Segmented Control? Then it will look exactly like the regular Buttons and the user will either be clicking on the Segmented Control and wonder why nothing happens or NOT click on the other buttons thinking they are all the same - and either one is just not going to work well.