In my opinion these two tactics are overlooked and not studied in enough detail. Imagine that you’re in the middle of a tough chess match. You notice that you can make a strong capture or check, unfortunately however one of your own pieces is in the way. That’s where a clearance sacrifice comes into play. We sacrifice one of our own pieces to clear a square, rank, or diagonal. Here two examples.
If whites rook were not in the way he could play 1. Qg7#. So how can white clear his rook out of the way? He can simply move it, but that would give black time to defend. There is one move however that leads to blacks defeat quite quickly. That move is 1. Rh7+. No matter how black captures, white plays Qg7#. A common theme in clearance sacrifices is to move the obstructing piece out of the way with check. Since our opponent must deal with the checking move it allows us to accomplish our goal. In the next diagram we can see an example by the great player Mikhail Tal.
It’s unfortunate for white that his queen is on the e6 square. If she weren’t there then white could play the knight fork Ne6+(remember forks?) Is there a solution to this problem? Tal thought there was and found 1. Qxf5! White captures the knight and clears the square at the same time. After this move black resigned.
Interference is a tactic where we disrupt the harmony of the enemy forces. Here is the classic example of interference from a brilliancy prize game.
White has some bank rank threats. Unfortunately blacks rook seems to be defending the bank rank fine. Richard Reti found a way to breakthrough with 1. Bf7+ Kh8 2. Be8!! There is no defense to the threat. Notice how whites bishop interferes with blacks bank rank defense. Interference tactics are somewhat rare, but they do happen. Interference can really be likened to the opposite of a clearance sacrifice. We put one of our pieces in harms way to accomplish a certain goal.