Difference between "my" and "local" keyword

Please refer below two examples:

1.

$a = 3.14159;
{
 local $a = 3;
 print "In block, \$a = $a\n";
 print "In block, \$::a = $::a\n";
}
print "Outside block, \$a = $a\n";
print "Outside block, \$::a = $::a\n";

# This outputs
In block, $a = 3
In block, $::a = 3
Outside block, $a = 3.14159
Outside block, $::a = 3.14159

2.

$a = 3.14159;
{
 my $a = 3;
 print "In block, \$a = $a\n";
 print "In block, \$::a = $::a\n";
}
print "Outside block, \$a = $a\n";
print "Outside block, \$::a = $::a\n";

# This outputs
In block, $a = 3
In block, $::a = 3.14159
Outside block, $a = 3.14159
Outside block, $::a = 3.14159

"local" will make global variable with the same name "invisible" temporarily,
"my" will create a new memory space and you can distinguish local and global scope variable.