diff --git a/src/diffusers/schedulers/scheduling_utils.py b/src/diffusers/schedulers/scheduling_utils.py
index f4103d4d62cc..424447efbdfc 100644
--- a/src/diffusers/schedulers/scheduling_utils.py
+++ b/src/diffusers/schedulers/scheduling_utils.py
@@ -25,6 +25,10 @@
 SCHEDULER_CONFIG_NAME = "scheduler_config.json"
 
 
+# NOTE: We make this type an enum because it simplifies usage in docs and prevents
+# circular imports when used for `_compatibles` within the schedulers module.
+# When it's used as a type in pipelines, it really is a Union because the actual
+# scheduler instance is passed in.
 class KarrasDiffusionSchedulers(Enum):
     DDIMScheduler = 1
     DDPMScheduler = 2
diff --git a/src/diffusers/schedulers/scheduling_utils_flax.py b/src/diffusers/schedulers/scheduling_utils_flax.py
index 9708c0883760..67c9dcc62414 100644
--- a/src/diffusers/schedulers/scheduling_utils_flax.py
+++ b/src/diffusers/schedulers/scheduling_utils_flax.py
@@ -27,6 +27,10 @@
 SCHEDULER_CONFIG_NAME = "scheduler_config.json"
 
 
+# NOTE: We make this type an enum because it simplifies usage in docs and prevents
+# circular imports when used for `_compatibles` within the schedulers module.
+# When it's used as a type in pipelines, it really is a Union because the actual
+# scheduler instance is passed in.
 class FlaxKarrasDiffusionSchedulers(Enum):
     FlaxDDIMScheduler = 1
     FlaxDDPMScheduler = 2