wordlist + rules VS large wordlist

[dupazonk]

Hi guys

I am new to the Hashcat and decided to do a small test.
I checked if will have same results with 'wordlist + rules' or with large wordlist which are generated from 'wordlist + rules'.

Here is what I got and what is not right:
hash - file with 50 milion ntlm hashes
word - file with 257823994 lines as wordlist
rule - file with 250 rules.
words-stdout - file with 64198174506 lines which contains all words from --stdout of 'word + rule'

Test #1
word + rule = 64198174506 combinations and 37.75% recovered

Test #2
words-stdout = 64198174506 combinations and 43.40% recovered

Attack was like that:
#1 hashcat -a 0 -m 1000 w 3 --potfile-disable hash.txt word.txt -r rule.txt -o output.txt
#2 hashcat -a 0 -m 1000  w 3--potfile-disable hash.txt word.txt -o output.txt

Did both tests twice and got same result at every time.

Can anyone explain why there is a difference?

Thanks