It depends on samba configuration. You should look at options "follow symlinks", "wide links" and "unix extensions". Enabling symlinks is a security hole, so be carefull or use other method like "bind mount".
Also I do not understand, you wrote
fstab entries are essentially similar and there is no basic difference in file/directory permissions on the two sides
What sides? Do you you have two systems or one?
You should change title to something like "Symbolic links not works with Samba" because as you mentioned they works on Linux as well between partitions.