Whey you are falling in a vacuum, it's not 1g, but 0g. That's what they experience on orbit. When you are falling with atmosphere resistance, it can be anything. Consider yourself jumping into water. You feel weightless when you are falling, but what do you feel when you hit the water? That's what happens when you hit atmosphere at 8km/sec.
The difference is between acceleration and g-force. Falling towards earth in a vacuum (or orbiting earth in a vacuum) you are experiencing 1g of acceleration but zero-g of g-force because you and your spaceship are accelerating together and you aren't meeting any mechanical resistance to the acceleration.
Once you start hitting atmo the velocity you've built up from your 1g of freefall meeting the resistance of the atmosphere creates g-forces.
