Checking out HEAD versus switching to it from a working copy of a branch

[Mahender Didwania]

Is there any difference between checking out the HEAD versus switching to it 
later from a branch (using cvs up -A) ?

I have a branch created from another branch and checked out as my working copy. 
 I wish to replace HEAD with the working copy, the working copy has no 
uncommitted changes.  I followed the instructions at 
http://kb.wisc.edu/middleware/page.php?id=4087 (section 'Replacing one branch 
with another').  But because the commit failed due to pre-commit checks 
configured by CVS admin here, I tried the alternative way of checking out HEAD, 
doing a merge again as per the instructions on the page referred to above and 
then thought it would be better to do a diff between the merge-result from my 
first attempt (where I had the branch checked out and later switched to HEAD 
before merge) and this attempt; and I found there were differences between the 
two post-merge situations.  So, is it the case that checking out a branch, then 
switching to HEAD, then replacing the working copy with the branch xyz is not 
the same as checking out HEAD and replacing the working copy with the branch 
xyz?

The descripton of what was done is as follows (assuming I had the branch 
checked out, my scenario 1 in above):

HEAD can be replaced with another using a similar syntax to a merge. 
Tag the end of your branch 
sandbox$ cvs tag merge_NEW_FEATURE_ADD_BRANCH
Move back to HEAD, or to the branch you want to REPLACE: 
To HEAD: 
sandbox$ cvs up -A
Do the replace. (Order is important. Note that the version that is being 
replaced comes first.) 
Replacing HEAD: 
sandbox$ cvs up -jHEAD -jNEW_FEATURE_ADD_BRANCH
Commit changes back to CVS. 
sandbox$ cvs ci

I read somewhere that merging using a tag will result in commit failure.  So, 
the merge uses the branch name and not the tag name as the argument to the 
second -j option.