One Monero block is (1 << 21) / 16 [Source (Lines 40, 43 and 90): https://github.com/monero-project/monero/blob/master/src/crypto/slow-hash.c#L40 ].
The Monero block reward = (M - A) * 2-20 * 10-12, where A = current circulation. Source: https://monero.stackexchange.com/a/4254/2828 .
With Monero the difficulty is dynamically adjusted so that Blocks are completed in 2 minutes.
"Difficulty is a numerical representation of how long on average it will take to create a valid block that satisfies the Proof-of-Work algorithm being used, it does not represent minutes or time per se. but instead is an integer number that makes the PoW calculation take longer to perform, this is adjusted by the nodes and miners so that on average it ensures the network creates blocks at a generally consistent rate.
This is calculated among all the nodes and miners in accordance with the globally agreed rules in the network, AKA consensus rules.
Miners that do not include this number in their difficulty calculations will not have their block validated and included by the rest of the network." - Source: https://monero.stackexchange.com/a/1494/2828 .
ZCash and Monero use different POW algorithms, comparing blocks solved or chances of success between the two isn't a good means to determine which is more profitable/difficult.
Try https://whattomine.com/ where you can say what equipment you have available and it will estimate your earnings for dozens of Cryptocurrency types simultaneously, including Monero and ZCash.
Example Mining Profitability Calculations:
For Ethereum:
Reward = ((hashrate * block_reward) / current_difficulty) * (1 - pool_fee) * 3600
For CryptoNote-based currencies (Bytecoin, Monero, Quazarcoin, DigitalNote, etc.):
Reward = ((hashrate * block_reward) / current_difficulty) * (1 - pool_fee) * 3600
For Bitcoin-like currencies (Bitcoin, Litecoin):
Reward = ((hashrate * block_reward) / (current_difficulty * 2^32)) * (1 - pool_fee) * 3600
"<YOUR HASHRATE> / (<YOUR HASHRATE> + <NETWORK HASHRATE>) x <BLOCKS PER 24H> x <BLOCK REWARD>"
Bitcoin : userHash/(difficulty*(2^32))*blockReward*3600*1000000000(hashFactor)
ETH: (userHash/difficulty)*blockReward*3600*hashFactor
Zcash: userHash/((difficulty)*solsPerDiff)*blockReward*3600*hashFactor (sollsPerDiff = 8192)
Monero: userHash/(difficulty*1e9)*blockReward*3600