What is the difference between ui-bootstrap-tpls.min.js and ui-bootstrap.min.js?

So, ui-bootstrap-tpls.min.js == (ui-bootstrap.min.js + HTML templates) required by the JavaScript code. If you only included ui-bootstrap.min.js, you will also need to provide your own HTML templates.

Otherwise you will see something like:

GET http://localhost:8989/hello-world/template/tooltip/tooltip-popup.html 404 (Not Found) angular.js:7073
Error: [$compile:tpload] http://errors.angularjs.org/undefined/$compile/tpload?p0=template%2Ftooltip%2Ftooltip-popup.html
    at Error (<anonymous>)
    at http://localhost:8989/hello-world/js/vendor/angular-1.2.0-rc.3/angular.min.js:6:453
    at http://localhost:8989/hello-world/js/vendor/angular-1.2.0-rc.3/angular.min.js:54:14
    at http://localhost:8989/hello-world/js/vendor/angular-1.2.0-rc.3/angular.min.js:64:438
    at A (http://localhost:8989/hello-world/js/vendor/angular-1.2.0-rc.3/angular.min.js:89:258)
    at A (http://localhost:8989/hello-world/js/vendor/angular-1.2.0-rc.3/angular.min.js:89:258)
    at http://localhost:8989/hello-world/js/vendor/angular-1.2.0-rc.3/angular.min.js:90:465
    at g.$eval (http://localhost:8989/hello-world/js/vendor/angular-1.2.0-rc.3/angular.min.js:98:272)
    at g.$digest (http://localhost:8989/hello-world/js/vendor/angular-1.2.0-rc.3/angular.min.js:96:142)
    at g.$apply (http://localhost:8989/hello-world/js/vendor/angular-1.2.0-rc.3/angular.min.js:99:100)

People have answered this question already, but I wanted to point out that starting with release 0.13.4, we've added the ability to provide your own templates on a case-by-case basis (i.e., each directive use, not application wide, though, the latter would not be hard to do).

The tpls tag means that the file also contains templates.

Here is an example:

ui-bootstrap.js

angular.module("ui.bootstrap"
 ["ui.bootstrap.transition"
"ui.bootstrap.collapse"
"ui.bootstrap.accordion"
"ui.bootstrap.alert"
"ui.bootstrap.bindHtml"
"ui.bootstrap.buttons"
"ui.bootstrap.carousel"
"ui.bootstrap.position"
"ui.bootstrap.datepicker"
"ui.bootstrap.dropdownToggle"
"ui.bootstrap.modal"
"ui.bootstrap.pagination"
"ui.bootstrap.tooltip"
"ui.bootstrap.popover"
"ui.bootstrap.progressbar"
"ui.bootstrap.rating"
"ui.bootstrap.tabs"
"ui.bootstrap.timepicker"
"ui.bootstrap.typeahead"]);
angular.module('ui.bootstrap.transition'
 [])

ui-bootstrap-tpls.js

angular.module("ui.bootstrap"
 ["ui.bootstrap.tpls"
 "ui.bootstrap.transition"
"ui.bootstrap.collapse"
"ui.bootstrap.accordion"
"ui.bootstrap.alert"
"ui.bootstrap.bindHtml"
"ui.bootstrap.buttons"
"ui.bootstrap.carousel"
"ui.bootstrap.position"
"ui.bootstrap.datepicker"
"ui.bootstrap.dropdownToggle"
"ui.bootstrap.modal"
"ui.bootstrap.pagination"
"ui.bootstrap.tooltip"
"ui.bootstrap.popover"
"ui.bootstrap.progressbar"
"ui.bootstrap.rating"
"ui.bootstrap.tabs"
"ui.bootstrap.timepicker"
"ui.bootstrap.typeahead"]);

angular.module("ui.bootstrap.tpls"
 ["template/accordion/accordion-group.html"
"template/accordion/accordion.html"
"template/alert/alert.html"
"template/carousel/carousel.html"
"template/carousel/slide.html"
"template/datepicker/datepicker.html"
"template/datepicker/popup.html"
"template/modal/backdrop.html"
"template/modal/window.html"
"template/pagination/pager.html"
"template/pagination/pagination.html"
"template/tooltip/tooltip-html-unsafe-popup.html"
"template/tooltip/tooltip-popup.html"
"template/popover/popover.html"
"template/progressbar/bar.html"
"template/progressbar/progress.html"
"template/rating/rating.html"
"template/tabs/tab.html"
"template/tabs/tabset-titles.html"
"template/tabs/tabset.html"
"template/timepicker/timepicker.html"
"template/typeahead/typeahead-match.html"
"template/typeahead/typeahead-popup.html"]);
angular.module('ui.bootstrap.transition'
 [])

For example: template/alert/alert.html

angular.module("template/alert/alert.html", []).run(["$templateCache", function($templateCache) {
  $templateCache.put("template/alert/alert.html",
    "<div class='alert' ng-class='type && \"alert-\" + type'>\n" +
    "    <button ng-show='closeable' type='button' class='close' ng-click='close()'>&times;</button>\n" +
    "    <div ng-transclude></div>\n" +
    "</div>\n" +
    "");
}]);