If you have Classifier theme, you should notice featured image slider on the front page sometimes it does not have the same image ratio. Basically it design for images that has a different height so it will still fit the featured panel slider. You can check Classifier demo site here : http://demo.colorlabsproject.com/classifier/
Featured panel slider image is depend on the height of the image, it is dynamically changed and follows the height of the current image.
On more featured panel section, the image is cropped and resized, so it would fit the thumbnail image. The best image width is 744px.
Images which is lower than that size will not be resized. The user have to submit an image higher or the same as that width to achieve the same height on every image.