What is the difference between the ultimate and allowable bearing capacity of the soil?

this equostion is very important

: the ulltimate one is

The biggest pressure borne by soil before collapsethe

allowable isThe biggest pressure can afford it mathematically  

The Ultamite Bearing Capacity of the soil is the max load which can be applied; and the Allowable Capacity an equation deviding the Utamite Capacity by the Safty factor and is therefore a saver load and assures to have a large enough quantity to prevent damage through settlement.

Please read below the answer I found on Wikipidia:

Bearing Capacity is the capacity of soil to support the loads applied to the ground. The bearing capacity of soil is the maximum average contact pressurebetween the foundation and the soil which should not produce shear failure in the soil. Ultimate bearing capacity is the theoretical maximum pressure which can be supported without failure;allowable bearing capacity is the ultimate bearing capacity divided by a factor of safety. Sometimes, on soft soil sites, large settlements may occur under loaded foundations without actual shear failure occurring; in such cases, the allowable bearing capacity is based on the maximum allowable settlement.

regulations and deflections

Ultimate bearing capacity is the maximum pressure that a foundation soil can withstand without undergoing shear failure. 

Safe bearing capacity is the safe extra load the foundation soil is subjected to in addition to initial overburden pressure.

Allowable bearing pressure is the maximum pressure the foundation soil is subjected to considering both shear failure and settlement.

Safe bearing capacuty of Soil: 

The maximum load that soil can bear without any settlements is called Safe bearing capacity of soil. 

Ultimate bearing capacity is a load at which soil starts displacing is called ultimate bearing capacity .

For more info you can click here to know about how to calcluate it in site etc safe bearing Capacity, ultimate and soil bearing  

The Ultimate Bearing Capacity of Soil is that which the particular sample of soil naturally possess.

The allowable Bearing Capacity of the Soil is that which is the minimum requirement of Load for particular structure.