What's the difference between an open stud brick, and solid stud brick? Should I watch out on which one I use?  
[![Brick, Modified 1 x 1 with Clip Vertical (open O clip) (part 30241b) and Brick, Modified 1 x 1 with Clip Vertical (part 30241)][1]][1]


  [1]: https://i.sstatic.net/VDUYl.jpg