How are the same parts used in different locations and How is the same piece used in different forms?

1- How are the same parts used in different locations?
I tried to explain this example in the video "use of the same part in different positions in different assemblies.mp4". Our aim here is to use common wheels in different positions in different assemblies. However, when we do this in CATIA V5, their positions change in other assemblies where it is used.

2-How is the same part used in different forms?

To explain this problem, I created the video named "Same semi product used in different form.mp4". In the video you will watch, you see two tube's of the same length made of the same material. These pipes are ordered in 2 pieces with the same part code. The problem we have is that we cannot use the same instances in different forms.

Thank you in advance for your speedy assistance.

​​​​​​​