Actually length doesn't decide, but rather total accumulated hashing power. This is because Bitcoin changes the difficulty per block over time to keep the time

Actually length doesn't decide, but rather total accumulated hashing power. This is because Bitcoin changes the difficulty per block over time to keep the time between blocks close to 10 minutes. This means that two chains can be equally long but have different amounts of accumulated difficulty. It even means that long blockchains can have low amounts of accumulated difficulty. But for short periods of time, less than ~2 weeks as it is for Bitcoin, the difficulty will not yet have changed and thus length = total difficulty for SHORT forks.