Question:
If i set the same password in both linux and Windows, is it easier for a hacker to break the windows password? If so why and how can i create a windows password in the same security level as Linux?


Answer:
There are two big reasons that Windows passwords are easier to crack. When passwords are stored in the computer they are hashed. Hashing a password adds some obscurity to the password. Windows uses MD4 to hash its passwords (without a salt) where as Linux uses 5000 rounds SHA-512 with a salt (last I checked). Essentially Linux uses a hash that has more possible outputs and added obscurity. If you don't know what hashing and salting is I'd suggest you look here.

As far as I know you cannot change this in Windows. With Linux.... well with Linux you could change it to store your password as cat no matter what.

A very simplistic example of what hashes look like is:
Lets say your password is 12345
Using MD4 windows would store the password as 23580e2a459f7ea40f9efa148b63cafb
With linux it would add a salt and store it as something that look like this (note this is the hash for 12345 done once without a salt)

3627909a29c31381a071ec27f7c9ca97726182aed29a7ddd2e54353322cfb30a bb9e3a6df2ac2c20fe23436311d678564d0c8d305930575f60e2d3d048184d79