Why is the Chinese and western zodiac so different?

Cali, Chinese zodiac and western astrology are two different systems. Each has its own principles. If you are a Chinese, you may believe Chinese zodiac. If you are a westerner, you may believe western astrology without any doubt. I don't think you should be bothered. The compatibility (no matter Chinese or western zodiac) may affect your relationship partially or even doesn't have any effect. True love conquers everything. Just forget about the compatibility and spend more time deepening your relationship.