Are the USToys one made of rubber instead of hard plastic?
I just went and double checked. The U.S. Toy ships are significantly larger than the Silent Death miniatures. They are definitely malleable in a way that to me feels more like rubber than soft plastic (they don't feel like army soldier plastic). The details on the U.S. Toy ships are identical to the Silent Death minis from Iron Crown.
The Silent Death miniatures from Iron Crown were originally cast in metal and later in hard plastic. Here is a link to detailed overhead line drawings of all of the Silent Death miniatures currently available from Iron Crown:
The minis at EM4 look like hard plastic. I wonder if they are authorized by or licensed from Iron Crown, or excess inventory.
U.S. Toy also sells these miniature space ships:
They are not the same design, but are much closer to the correct size for Silent Death. I have a set of these as well. They are made of a somewhat soft and very flexible rubber-like material (silicone?).