What is the difference between water and the blood of Jesus?
The shed blood of Jesus is the reason mankind has a hope of salvation. It paid the price necessary to purchase us back from the debt we incurred by our own sins. "In Him we have redemption through His blood, the forgiveness of sins, according to the riches of His grace" (Ephesians 1:7). "Knowing that you were not redeemed with corruptible things, like silver or gold, from your aimless conduct received by tradition from your fathers, but with the precious blood of Christ, as of a lamb without blemish and without spot" (I Peter 1:18-19). Man is unable to obtain salvation on his own. It took the blood of God's own Son to rescue us from our sinful mess.
Water (baptism) is the method God selected for men, willing to come to Him for salvation, to accept the gift God has freely offered. "Or do you not know that as many of us as were baptized into Christ Jesus were baptized into His death? Therefore we were buried with Him through baptism into death, that just as Christ was raised from the dead by the glory of the Father, even so we also should walk in newness of life. For if we have been united together in the likeness of His death, certainly we also shall be in the likeness of His resurrection, knowing this, that our old man was crucified with Him, that the body of sin might be done away with, that we should no longer be slaves of sin. For he who has died has been freed from sin. Now if we died with Christ, we believe that we shall also live with Him, knowing that Christ, having been raised from the dead, dies no more. Death no longer has dominion over Him. For the death that He died, He died to sin once for all; but the life that He lives, He lives to God. Likewise you also, reckon yourselves to be dead indeed to sin, but alive to God in Christ Jesus our Lord" (Romans 6:3-11). It is in baptism that we contact the blood of Christ and have our sins washed away (Acts 22:16).