The module to provide node comparison functionality on user request. It compares the values of the fields of nodes.

In a settings you can specify which fields are allowed to compare. Separately for each type of node.
There is a possibility control the number of elements being compared.
Using AJAX for add / delete / clear the selected nodes to compare.
Customizable text for links to add / remove items to compare.
Integration with Views (“Add to Compare” link).

On the page of your site with a list of available modules, Node Compare can be found in the group of "Content".
After installing the module you can configure settings by navigating to: Administration » Configuration » Content authoring » Node Compare settings (admin/config/content/node_compare).
Set the region to display the block which to display a deferred items to compare.
Set permissions for existing user groups to use the comparison. (admin/people/permissions#module-node_compare)
Set the display settings for the link to "add / remove" on "Manage Display" settings page (for a node content type).

Node Compare

Issues