Is there a difference in the treatment between alt and title attributes for <img> tags in terms of SEO implications?
First, to be terminologically clear, there is no such thing as an alt tag. It is an alt attribute within an img tag.
Secondly, title attributes are not considered important in the SEO rankings, as it can be easily spammed (you can put a title attribute on many different tags).
Alt attribute is for images and title attribute is for links. Alt has positive effect in terms of SEO and title does not.