To reduce confusion between tires that are all season or mud and snow, the Rubber Association of Canada developed an icon of a snowflake set against a mountain.
Don’t bother with winter tires unless you are prepared to replace all 4 tires. Replacing only tires on the drive wheels can cause uncertain and dangerous handling, increasing the likelihood of loss of control in slippery conditions.
Winter tires have thousands of tiny cuts in the tread surface called sipping. These sipes provide extra bite on slippery ice surfaces. All season tires work reasonably well but once you have tried a good winter tire, your confidence level in winter driving will increase.
Mixing tires with different tread patterns, internal construction and size degrades the stability of the vehicle and should be avoided.