Why is absorption spectrum of beta-carotene different from Zeaxanthin?

Here are the molecular structures of beta-carotene and zeaxanthin


[![beta-carotene](https://i.stack.imgur.com/r6lZL.png)](https://i.stack.imgur.com/r6lZL.png)[![zeaxanthin](https://i.stack.imgur.com/S8hNQ.png)](https://i.stack.imgur.com/S8hNQ.png)


These molecules only differ in the OH groups and the conjugated backbone length is exactly the same. I read that the absorption spectrum of a molecule is decided by the conjugation length. How is it then, that the absorption spectrum of the two molecules are different as shown below:


[![enter image description here](https://i.stack.imgur.com/h8ngi.jpg)](https://i.stack.imgur.com/h8ngi.jpg)


