Miracles of God and magic may both appear similar on the surface, but are from different supernatural sources. Moreover, deceivers abound who do fake miracles where nothing supernatural occurs, or where occult signs and wonders are performed for temporal gain.
Regardless of what one calls it, the very existence of our universe requires a 'miracle'. Foundational scientific laws of this universe, such as the law of cause and effect, and the first and second laws of thermodynamics, do not allow for our universe to have 'created' itself, since the amount of mass/energy in our universe is absolutely fixed according to the first law. The universe can't be infinitely old either, because otherwise it would already be decayed and dead according to the second law. If one projects backwards in time, then, our universe came into existence in extremely complex order, cannot have come from itself, and according to cause and effect, must have originated from a cause equal to or greater than the effect.
Unlike religious and political leaders throughout history, Christ's claim to be God and ability to work miracles is based on His identity as the unique Creator and Author of life. The kind of miracles done by Christ contradict the pervasive scientific laws of thermodynamics by creating something out of nothing and life from non-life. Christ's claim as the Savior and Messiah is based foundationally on His identity as the supernatural Creator, which is why He has complete authority over the natural scientific laws He created.
About miracles and magic, the Bible teaches Satan is not only the enemy of God, but also an expert counterfeiter of God, to deceive people to the greatest degree possible. Miraculous events are recorded as coming from God, but from created beings as well, such as Satan. In the book of Job, Satan is recorded as having controlled the weather, and in Revelation (yet future), his human servants call fire down from heaven.
When people claim 'natural' or 'supernatural' miracles that bring glory and financial profit to men, you can know they are not of God. As Christ predicted, deceivers are increasingly popular and convincing, so much more spiritual discernment is needed to see God clearly and recognize increasingly clever religious, political, and pseudo-scientific impostors that masquerade in His name.