It is all about working copy versions. If your local working copy format version for Subclipse matches the one for TortoiseSVN you can use your checked out local working copy as they are (TortoiseSVN indicates this by showing icons for the files in your explorer). However you should double-check this in the Subclipse and TortoiseSVN home pages respectively.
If your working copy format versions match you can also switch between Subclipse and TortoiseSVN as you see fit.
Now if this doesn't work for you already, there is a mismatch between the working copy formats. With your scenario this is what you need to do:
- Your Subclipse working copy format version is lower than your TortoiseSVN version. If that is the case all you need to do is to upgrade the working copy format which TortoiseSVN can do for you. If I remember correctly TortoiseSVN will suggest to do this automatically, but I know for sure that you can use the command 'svn upgrade' on a command prompt on your working copy. After running this it will no longer work for your Subclipse until you upgrade it to match the same working copy format version.
- Your Subclipse working copy format version is higher that your TortoiseSVN version. I suggest you upgrade to a later (the latest?) version of TortoiseSVN.
NOTE! In all this, the important is not which version if Subclipse or TortoiseSVN you are running. The important is which Subversion version it is linked against. On http://tortoisesvn.net/ you can see that "TortoiseSVN 1.8.2 has been released. It is linked against Subversion 1.8.3". In this case the 1.8.3 is the important version and is using the 1.8 working copy format.