Regex for Hive built in functions giving different result

hive> show functions like 'ad?*';
OK
abs
acos
add_months
aes_decrypt
aes_encrypt
and
array
array_contains
ascii
asin
assert_true
atan
avg
Time taken: 0.005 seconds, Fetched: 13 row(s)
hive> show functions like 'ad*';
OK
add_months
Time taken: 0.005 seconds, Fetched: 1 row(s)