Flexural cracks are due to bending. Assuming the material is concrete the tension face (Usually bottom for positive Bending and top for negative bending)face is vulnerable to cracks due to negligible/low tensile strength of concrete.
This is the reason why we use reinforcement at tension face to make best use of both the materials(concrete & steel) in regular reinforced concrete composite construction.
I do not understand what do u mean by potential? you may elaborate on it.
If so, and you're talking about reinforced concrete, then the main diffeence is this. As Bannu has explained, flexural cracking happens only in the tension zone of a bending member such as a beam, so it only goes maybe half way through the concrete. The other half is in compression and is not cracked. But tensile cracking may occur in reinforced concrete in tension rather than bending. This may have cracks all the way through, which could have implications for durability or leaking.
Tesile cracks do occur in concrete due to bending. Bending causes tesion in extreme fibers.
For example in slab the bending tension would be at the bottom fibers which leads to cracking of concrete if inadequate reinforcement is provided or the stress in concrete exceeds the modulus of rupture.
