The difference between Separate and Split

Separate as an adjective:

Apart from (the rest); not connected to or attached to (anything else).

Separate as an adjective (followed by “from”):

Not together (with); not united (to).

Separate as a verb (transitive):

To divide (a thing) into separate parts.

Separate as a verb:

To disunite something from one thing; To disconnect.

Separate as a verb (transitive):

To cause (things or people) to be separate.

Separate as a verb (intransitive):

To divide itself into separate pieces or substances.

Separate as a verb (obsolete):

To set apart; to select from among others, as for a special use or service.

Separate as a noun (usually, in the plural):

Anything that is sold by itself, especially an article of clothing.

Split as an adjective:

Divided.

Split as an adjective (algebra, of a [[short exact sequence]]):

Having the middle group equal to the direct product of the others.

Split as an adjective (of coffee):

Comprising half decaffeinated and half caffeinated espresso.

Split as an adjective (stock exchange, of an order, sale, etc.):

Divided so as to be done or executed part at one time or price and part at another time or price.

Split as an adjective (stock exchange, historical, of quotations):

Given in sixteenths rather than the usual eighths.

Split as an adjective (London stock exchange):

Designating ordinary stock that has been divided into preferred ordinary and deferred ordinary.

Split as a noun:

A crack or longitudinal fissure.

Split as a noun:

A breach or separation, as in a political party; a division.

Split as a noun:

A piece that is split off, or made thin, by splitting; a splinter; a fragment.

Split as a noun (leather manufacture):

One of the sections of a skin made by dividing it into two or more thicknesses.

Split as a noun (gymnastics, cheerleading, dance, usually in the phrase “to do the splits”):

A maneuver of spreading or sliding the feet apart until the legs are flat on the floor 180 degrees apart, either sideways to the body or with one leg in front and one behind, thus lowering the body completely to the floor in an upright position.

Split as a noun (baseball, slang):

A split-finger fastball.

Split as a noun (bowling):

A result of a first throw that leaves two or more pins standing with one or more pins between them knocked down.

Split as a noun:

A split shot or split stroke.

Split as a noun:

A dessert or confection resembling a banana split.

Split as a noun (US):

A unit of measure used for champagne or other spirits: 18.75 centiliter or one quarter of a standard .75 liter bottle. Commercially comparable to 1/20th gallon, which is 1/2 of a fifth.

Split as a noun:

A bottle of wine containing 0.375 liters, half the volume of a standard .75 liter bottle; a demi.

Split as a noun (athletics):

The elapsed time at specific intermediate points in a race.

Split as a noun (video games):

The elapsed time at specific intermediate points in a speedrun.

Split as a noun (construction):

A tear resulting from tensile stresses.

Split as a noun (gambling):

A division of a stake happening when two cards of the kind on which the stake is laid are dealt in the same turn.

Split as a noun (music):

A recording containing songs by multiple artists.

Split as a verb (transitive, ergative):

Of something solid, to divide fully or partly along a more or less straight line.

Split as a verb (intransitive):

Of something solid particularly wood, to break along the grain fully or partly along a more or less straight line.

Split as a verb (transitive):

To share; to divide.

Split as a verb (slang):

To leave.

Split as a verb:

To separate or break up.

Split as a verb (algebra, transitive, and, intransitive, acts on a [[polynomial]]):

To factor into linear factors.

Split as a verb:

To be broken; to be dashed to pieces.

Split as a verb:

To burst out laughing.

Split as a verb (slang, dated):

To divulge a secret; to betray confidence; to peach.

Split as a verb (sports):

In athletics (esp. baseball), when both teams involved in a doubleheader each win one game and lose another game.