Review pops are very different from Rep Kahuna Website Widgets. Below are some major differences between the two:

Review Pops

A tool to optimize your lead generation strategy to help you find and connect with prospects by offering a review pop free for 30 days. This gives you an opportunity to offer the review pop for a fee for the rest of the year and/or an upsell to the full Reputation Marketing package (which you would fulfil using Rep Kahuna.
Review Pops will only show 5-star reviews from Google my Business - not from any other review directories.
Review Pops styles are limited to Review Pops and Rating Pops

Website Widgets inside Rep Kahuna

This is an Upsell Strategy. Widgets inside of Rep Kahuna have more options including video widgets, on-page widgets, block widgets, and sidebar widgets.
The Website Widgets will show feedback collected actively through request campaigns submitted through feedback pages as well as reviews collected from various directories.
Website Widgets will Include Review Pop-up and Rating Pop-up as well as Video Pop-up, Onpage Widget options like Sidebar Widget (with and without videos), Block Widgets (with or without videos), Trailing Review Sheet (with and without pages), more design options, and more customizations.