This is a very common question and the answer is there is very good compatibility between CircuitStudio (CS) and Altium Designer (AD).
|Schematics||.schdoc||This type of file can be opened by both CircuitStudio and Altium Designer.|
|These types of schematic libraries, PCB libraries and integrated libraries can be open by both CircuitStudio and Altium Designer.|
|CS PCB||.cspcbdoc||CircuitStudio PCB files can be imported into Altium Designer v16 or later.|
|AD PCB||.pcbdoc||CircuitStudio can import PCBs from Altium Designer provided they were saved in Binary 5 format.|
Transferring PCB data between CircuitStudio and Altium Designer involves an import process going either way so it is always wise to very thoroughly check the imported document for errors. This advice applies not just to CS and AD but to any CAD package that imports or translates data into its own native format. It is not recommended to casually transfer a design on a regular round trip basis between packages.
AD had many advanced features not available in CS, for example flex-rigid board design and advanced design rules. The design rules have differences between the software version so they need to be inspected to ensure they are still suitable for the design. Having said that, the results are typically very good. Usually the only changes required are cleaning up extra default objects that are created, for example, extra default design rules for each type of design rule, or an extra layer stack when importing a flex-rigid design that had been translated. Don't expect every possible board designed in AD to transfer across to CS and be fully editable. Any design that keeps to the feature set available in CS should transfer across and be fully editable and transfer back again.
The binary 5.0 file is an "older" format, so when this is imported into CircuitStudio, warnings will display to show the areas to check, for example: "CAUTION - Via connections to both hatched and solid signal layer polygons are now controlled by the polygon connect style rule. Re-pouring polygons may result in physical copper differences.". Since the file was originally in a newer format which already has the newer type of polygon connection style rule, these cautions can usually be ignored.
When a file is edited and saved in CircuitStudio, the features in CircuitStudio usually save the objects in a way that Altium Designer can import again. For example, you'll remove the extra default design rules to correct the design for use in CircuitStudio. Then the design rules that are modified or created in CircuitStudio will still work correctly when the file is converted back to Altium Designer format. During the import back to Altium Designer, appropriate Cautions will be displayed for the case where objects or design rules have changed and need to be checked.
Objects known to be damaged when saving the file in CircuitStudio are the objects on the Board Planning Mode to specify rigid-flex boards. CircuitStudio doesn't support this mode or the flex board feature. These objects are stripped out and would need to be placed again when bringing the board back into Altium Designer. There could be other more subtle objects affected that haven't been documented. For example, say if an object such as a Dimension object was changed significantly in a new Altium Designer version, the dimension could be affected when editing the file in CircuitStudio.
In summary, despite all these warnings, there is very good compatibility between CircuitStudio and Altium Designer. We encourage you to download the free trials and see for yourself.