I'm confused by these two complete radicals listings. Why are there some differences?

[Ness]

Hey. I'm trying to get into familiarizing myself with radicals to try and help me memory along while learning Chinese characters. So I went to two websites that have a complete listing of the 214 radcials. However I'm confused because of the radicals have completely different words for the symbol. Take #40 for instance. Which is 宀 for roof. One of the lists has it as gai4, while the other has it as mian2. There are some others too like #43 or #104. Take a look for yourself.

 

http://www.yellowbridge.com/chinese/radicals.php

 

http://www.archchinese.com/arch_chinese_radicals.html

 

Anyone know the reason behind this? Would appreciate the help.

[xiaokaka]

The pinyin for 宀 is listed in dictionaries as mián, however ordinary Chinese people doesn't know that (as it's not used as an independent character) and they refer to it as 宝盖 bǎo gài ("The lid on the character 宝"). Maybe that's where gài comes from, the reading of 盖.