"-it" is equivalent to "<" "-gt" equivalent to ">" "-eq" equivalent to "="???

In the shell script experiment, a problem was found:

"-it" equivalent to "<"??

"-GT" equivalent to ">"??

"-eq" is equivalent to "="??

Take a look at experiment 1 below:

#!/bin/sh
A=$1
B=$2
If [-Z $a]| | [-Z $b]
Then
echo "Please enter 2 number ..."
Exit 1
Fi

if [$a = $b]
Then
echo "Number A = number B"
else if [$a-lt $b]
Then
echo "number A<number B"
else if [$a-gt $b]
Then
echo "number A>number B"
Fi
Fi
Fi

Results:

[Root@localhost Shell Experiment]#./FI 2 3
Number A<number b
[Root@localhost Shell Experiment]#./FI 3 2
Number A>number b
[Root@localhost Shell Experiment]#./FI 3 3
Number A = number B

Lab 2:

#!/bin/sh
A=$1
B=$2
If [-Z $a]| | [-Z $b]
Then
echo "Please enter 2 number ..."
Exit 1
Fi

if [$a = $b]
Then
echo "Number A = number B"
else if [$a < $b]
Then
echo "number A<number B"
else if [$a > $b]
Then
echo "number A>number B"
Fi
Fi
Fi

Results:

[Root@localhost Shell Experiment]#./FI 2 3
Number A<number b
[Root@localhost Shell Experiment]#./FI 3 2
Number A<number b
[Root@localhost Shell Experiment]#./FI 3 3
Number A = number B

Conclusion:

"-it" equivalent to "<"??

"-GT" equivalent to ">"??

"-eq" is equivalent to "="??

They are not equivalent, but what the reason is really do not understand, perhaps the rules of the grammar, the request of expert guidance ...