Ice cream depends on the fat content and the ice crystal formation. Fat content gives you the creamy texture when the ice cream melts in your mouth.
The ice crystal that forms the ice cream should be very small. Ice crystal in the ice cream is typically so small that we do not even notice.
How do we evaluate the presence of ice crystal? We can taste the ice cream. If the crystal is small enough, then the ice cream would have a smooth texture. With a large ice cream, unevenness can be felt.
Do you aware that ice cream need to be kept strictly under cool storage? Ice cream is produced at a very low temperature to give rise to the small crystal formation. Our fridge at home do not support the low temperature that an ice cream manufacturer could. That is why when ice cream is taken out from the fridge and melted, it can never get back to its original condition.