compair data from vector3

Hello, i got a question about vector3.
I want to know 1 of the coordinate from the vector3 is changed so i want to compair 2 different vector3 but it only needs to look at 1 of the vector3 data parts. so for instance i got (301.3,501.6,70.3) i only want to look at the first 1 the 301.3 and if its different from a second vector3 data i got. Any tips or ideas?

if

var yourVector : Vector3;

then

yourVector.x
yourVector.y
yourVector.z

can be used.