What is the difference between Udim2 and Vector 3?

Before I explain, UDim2 does not have a Z coordinate.

UDim UDim stands for Universal Dimensions. UDim basically is the position and size of GUIs. It takes 2 parameters: Scale and offset.

UDim2 UDim2 is the same thing as UDim but it represents 2 UDims with a 2 dimensional coordinate plane with x and y coordinates. UDim2 has 4 parameters: xScale, xOffset, yScale, yOffset.

Vector3 Vector3 represents a 3 dimensional position of an object not including rotations.

To put it simply, UDim and UDim2 are positions for GUIs and Vector3 is positions for 3D objects.

UDim2 does not have Z, and has four parameters. It is used for guis only, because it is a 2d object simply on the player's screen. The four params are X Scale, X Offset, Y Scale, and Y Offset.

Vector3 is for Part positions, which are in a 3d environment. It takes three parameters: X, Y, and Z.

UDim2: UDim2.new(0, 0, 0, 0)

Vector3: Vector3.new(0, 0, 0)

Udim2 is for positioning a GUI while Vector3 is for positioning a part