Your mass size difference from mammogram to ultrasound

I am curious to find out of other’s mammogram and ultrasound size differences and if your outcome was vastly different as a result. As of yet, malignancy hasn’t been ruled out. Here are my measurements:

My very first diagnostic mammogram was at a hospital breast screening clinic on August 15, 2018 stating a mass of 4mm (with mildly lobulated margins). On August 15 the ultrasound stated the mass as 1.5 x 0.8 x 1.3 cm. On October 4, I had a second ultrasound done at another breast clinic associated with a cancer hospital and a new second mass was found 1 cm away from my original (was only told it was 0.7 cm). I am still waiting for those results and have my surgeon’s appointment October 17 to get my new findings and measurements. Has anyone else had such varying results? I’ve never had a mamogram previous to this and I’m telling myself that this is normal, but a part of me is scared by these vast changes. Thanks.