They're different items in the game, which allow you to upgrade event buildings to the next age(s).
What you need to be aware off:
The Renovation Kit upgrades one event building to your current age - even if the building is multiple ages underneath your current age.
Example: Your current age is the Colonial Age and you want to upgrade a building from the Iron Age. It will be set to the Colonial Age with the Renovation Kit.
One Up Kit
The One Up Kit upgrades one event building to the next building age and not to the player age.
Example: Your current age is the Colonial Age and you want to upgrade a building from the Iron Age. It will be set to the Early Middle Age with the One Up Kit.
Special Building Upgrade Kits
We have various Special Buildings in the game, which can be upgraded to another level, like the Cider Mill, the Pillar of Heroes or the buildings from the Cherry Garden Set and more. Every of those buildings has their own upgrade kit, which upgrades them to the next level.
During this upgrade, the buildings are also set to the current player age.
Example: Your current age is the Colonial Age and you want to upgrade the Cider Mill (Iron Age) with the Cider Mill Upgrade to the Blooming Cider Mill. The Blooming Cider Mill will be in Colonial Age, too.
How can I use the different Upgrade Kits?
All different types of Upgrade Kits are used the same:
1. Open your inventory and search for the wanted Upgrade Kit. The click on the 'Use'-Button:
2. All buildings, which can be upgraded by the selected item are marked with a star in your city.
3. Click on the building you want to upgrade to the next age and confirm the process.