Are EDX and DX the same register?

Sorry for the ignorant question, but I'm rather confused about x86.

Is EDX essentially the same register as DX?
I understand EDX is 32 bit while DX is 16 bit.

If I move 0x1 to EDX would 0x1 also be in DX?

Also, if you're on a 64 bit system, EDX is the low 32 bit of the RDX register, which is a 64 bit register.

You could think of it as pointers:

long theRealRDX;
long * rdx = &theRealRDX;
int * edx = (int*)&theRealRDX;
short int * dx = (short int*)&theRealRDX;
char * dl = (char*)&theRealRDX;

except for high part erasure mentioned in nrz comment

[76543210 76543210 76543210 76543210 76543210 76543210 76543210 76543210] bits
[ RDX ]
[ EDX ]
[ DX ]
[ DH ][ DL ]

DX is simply the lower 16b of EDX :)

mov EDX, 0x1; --> DX = 0x1
mov EDX, 0x12345678; --> DX = 0x5678