Xiang is used as " to would like "

eg. I would like a cup of tea - wo xiang he yi bei cha
Whreas, Yao is used as " to want "
eg. I want a cup of tea. - wo yao he cha
The difference is subtle, but want (yao) is more demanding.
Literally xiang means 'think' so it's like saying 'I think I'd like a cup of tea' - it's more polite
yao can also mean 'going to' (same character) "I'm going to see my grandpa" - "wo yao kan wo yeye"


 However, people sometime use those words without that clear distinguish in mind.

 我要去看电影 or 我想去看电影 or 我想要去看电影


PS. What @Garry Andres said is not correct :  If you say, "Wo xihuan he cha" it means generally I like tea/to drink tea. A subtle but important difference.

i want and I would like: wo yao and wo xiang yao means the same in Chinese. 

love - ai - pronounced "eye".

Chinese characters, or even writing have always been a challenge for me but I will attempt it as phonetically correct as possible.  I hope it helps:

"want to" - woh yeow

"would like" - woh see hwan

from listening to audio tapes I want or I would like is wo xiang yao