you can always do things such as subtracting DE from HL to compare 16 bit numbers and look at different flags.  Also, I suggest from now on, you rename resolved threads to something like "Assembly questions" rather than a whole new thread per small question

Load the value to HL (since that's two bytes), load the second value to either DE or BC, reset the carry flag, and use SBC to subtract the values. For example,

    LD HL,256    ; Two-byte number
    LD DE,257    ; Another two-byte number
    OR A    ; Reset carry flag
    SBC HL,DE    ; Subtraction with carry
    JR C,Carried    ; This will get executed because HL-DE is less than zero


CPDEBC:
    push de
    ex de, hl
    or a
    sbc hl, bc
    ex de, hl
    pop de
    retPreserves all registers, etc, and sets flags just like CP.

Sorry don't use XOR A. Not sure what I was thinking

OR A does the binary OR comparison of A to itself. All you have to know about it is that it resets the zero and carry flags (that's pretty much all it's used for)

oh yeah can you explain what's "or a" or "xor a" is? i dont know where to learn about them.

Those involve Bitwise Arithmetic.  It modifies numbers based on their binary values.
The following:
XOR B
Will apply XOR logic on A and B.  The logic is as follows, using registers A and B for examples:
Value of A: 11110101
Value of B: 10011011
AND
A AND B will preserve the ones in B and overwrite the zeros in A. (1 and 1 = 1, 0 and 0 = 0, 1 and 0 = 0)

    11110101 (A)
and 10011011 (B)
------------------
    10010001

OR
OR does the opposite: (1 or 0 = 1, 0 or 1 = 1, 0 or 0 = 0)

    11110101 (A)
or  10011011 (B)
------------------
    11111111

XOR
XOR toggles the bits in A that are 1 in B. (1 xor 0 = 1, 0 xor 1 = 1, 1 xor 1 = 0)

    11110101 (A)
xor 10011011 (B)
------------------
    01101110

Sure thing.  Make sure you look back over it again, there were about 10 edits

Since it hasn't been mentioned, (though it's been stepped around), here is calc84's CP HL, DE:
or a ;reset carry flag
sbc hl, de
add hl, de
This one is small enough that it doesn't need it's own call, so just put it inline like you would CP A. And just like SirCmpwn said, this messes with the flags in the exact same way that CP A does.