**Feature tests take precedence over feature rollouts**. This means that if your feature has both a feature test and rollout, the feature test is evaluated first. If a user does not qualify for the feature test, the rollout is evaluated.
The table lists the differences between feature tests and rollouts.
|Column Title||Feature test||Feature rollout|
|Purpose||Lets you gather metrics data so you can compare multiple variations.||Lets you deploy a feature that you've already tested or measured some other way, such as qualitative feedback.|
|User impressions||When a user is assigned to a feature test, Optimizely sends an impression so that information is recorded in your test results.||When a user is assigned to a rollout, Optimizely does not send an impression. This means that extra network traffic and test results aren't generated. **Note: Rollouts do not count against your impressions limit**.|
|Variations||Test multiple variations—on versus off, or a multivariate test of different configurations||Only toggles the feature on or off.|
## Example scenario
To understand how this works in practice, imagine the following scenario. You've deployed a feature to your application and you've created both a feature test and rollout for that feature:
Feature test running with an audience and a traffic allocation
Rollout running with an audience and a traffic allocation
A series of users are handled by your application and are evaluated according to their audience attributes and your feature test and feature rollout rules. The table depicts all possible outcomes.
|User||Feature Test Audience||Feature Test Traffic Allocation||Feature Rollout Audience||Feature Rollout Traffic Allocation||Result|
## Is Feature Enabled method
Feature tests and rollouts are both triggered using the `
Is Feature Enabled` method.
## Interactions in multiple feature tests
In each environment, you can only run one feature test on each feature at a time (meaning, you can't run two tests on the same feature simultaneously) unless your feature is assigned to a [mutually exclusive group](🔗). If you try to launch a second feature test while another feature test is running, you’ll see a warning that only one feature test is allowed at a time—unless the tests are mutually exclusive.
[Use mutually exclusive groups](🔗) to run concurrent production feature tests. If feature tests are running in a mutually exclusive group, Optimizely evaluates a user’s mutually exclusive group first in the order of operations after calling the `
Is Feature Enabled` method. After the mutually exclusive group is assigned, Optimizely evaluates the feature test first. If a user does not quality for the feature test, the feature rollout is evaluated.
Note that you can have as many draft, paused, and archived tests on a feature as you like.