diff --git a/Review-guidelines.md b/Review-guidelines.md
index 8c7dac3..339a2e4 100644
--- a/Review-guidelines.md
+++ b/Review-guidelines.md
@@ -10,6 +10,16 @@
 * Add a label to classify the PR if it is fix or enhancement, logger to another part of code so reviewers can simpler take it according to their domain of expertise...
 * Add milestone where it shall fit so we can put it to timeline, mainly distinguish if it goes to closes bugfix release 1.0.x or feature release 1.x.0
 
+### Feature vs bugfix
+
+Each of them has its own label and accordingly, they shall be put into a milestone - semantic versioning (`1.F.0`) for features and (`1.F.B`) for bug-fixes.
+- **Features**:
+    - all API changes (add or remove public argument, class method, etc.)
+    - behaviour changes - function does something else, or parameters accept another value ranges/types
+- **Bugs**:
+    - update behaviour of a function to work as expected/desired
+    - fix crashes with expected input arguments
+
 ## General principles 
 
 * **We value everyone putting time and effort into PyTorch Lightning, but not every change should be included.**