Hello,
1) Dimensions of the one image are 2560 × 1920, dimensions of the other – 2560 × 1973. That’s why height is different. Either crop images to the same dimensions using any graphic editor before uploading them to your media or use the crop option for the grid images only at the Appearance > Customize > WooCommerce > Product Images, for example http://prntscr.com/rtzdz1
2) Use the Massive addons tabs element http://prntscr.com/rtzgkw if you want to get more options for the tab design customization https://massive.mpcthemes.net/tabs/ Default WPBakery tabs element does no have any additional options to manage this.
Regards