You can Copy and Paste the configuration.
Importing an export Is NEVER a good idea, particularly when the two devices are not the same, but - more generally - usually the destination device has some minimal configuration and importing the export from the old device could create conflicts.
A suitable procedure Is to compare the exports from the two devices and then Copy and Paste only the differences, in sections, a section at the time.
I just posted a couple spreadsheets that could be of use in such a situation, here:
http://forum.mikrotik.com/t/configuration-parser-spreadsheet/183922/1
but they are only tools that can help, not a fail- or fool- proof solution.
You need to be careful with interface names and interface lists as you risk to lock yourself out, you can set temporarily Winbox access allowed to “all” interfaces while you do the Copy/Paste.