Hi
@nikki, this may well be because the different versions you are looking at are in different keys, this is normally done to suit a singers range.
Fewer chords might also mean it has been simplified to omit some of the less important chords.
Also, the quality of the teaching (and hence the chords) varies a great deal from tutor to tutor and some chords might just be wrong in some videos.
At the end of the day, have a look around on YouTube and choose a video and teacher that is suited to the way you want to learn.
I have actually made two tutorials for this song, a beginner-friendly version in the key of C (which is not a good key for me to sing):
With a play-along video with the words and chords on the screen at:
And also a definitely much harder version in the key of A, which then changes key to Bb (which are much better keys for me to sing):
And the accompanying play-along with the words and chords on the screen at:
You will see that, although it is exactly the same song, the chords are very different in both versions.
I hope that makes sense.