Beginner Question: Fake Arduino Uno and Missing Parts… Should I Worry?

Today I bought an Arduino kit for $35. When I opened it, I realized the Arduino Uno board isn’t original. I could tell because I compared it with an original one I got from a friend. Also, three sensors were missing: the infrared sensor, the flame sensor, and the ultrasonic sensor.

Is this normal? And is there any practical difference between this board and an original one? I’m a beginner and just want to learn.