I think when you have a large piece of extravasated silicone gel outside the fibrous capsule it appears as a hypoechoic pool and when the silicone gel is more integrated into the tissue it makes the snow storm appearance.
In other words if you just have a small amount of silicone gel integrated into native breast tissue it looks like snow storm and when there is a larger volume “puddle”it looks more like silicone gel in the implant and has a hypo / anechoic appearance.