In brief:

Arminianism says God gives prevenient grace to all people, which overcomes total inability enough that they can freely respond to the gospel.

Provisionism says people do not need a separate, universal prevenient grace in that sense, because God has already made sufficient provision through things like:

• the gospel itself,
• the Holy Spirit’s conviction,
• divine revelation,
• and humanity’s God-given responsibility to respond.

So the main difference is this:

Arminian:
Humans are so fallen that they cannot respond to God unless God first gives a special enabling grace to all.

Provisionist:
God has already provided all that is needed for a genuine response, so an extra doctrine of prevenient grace is unnecessary.

A second difference is often this:

Arminianism is historically tied more closely to the classic doctrines of Jacob Arminius and later Remonstrant theology.
Provisionism is usually presented more as a non-Calvinist alternative that rejects both Calvinistic irresistible grace and classical Arminian prevenient grace.

Very simply:

• Arminianism = non-Calvinism with prevenient grace
• Provisionism = non-Calvinism without classical prevenient grace

If you want, I can also give you a very short table: Calvinist vs Arminian vs Provisionist.

Generally:

Arminianism:
Usually does not hold to “once saved, always saved.”
Classic Arminian and especially Wesleyan Arminian theology usually teaches that a true believer can fall away through persistent unbelief or apostasy.

Provisionism:
Usually does not require rejection of “once saved, always saved.”
Many Provisionists, especially in Baptist settings, do affirm eternal security, meaning a true believer remains saved.

So in very simple form:

• Arminianism: commonly conditional security
• Provisionism: often eternal security, though not strictly because of Provisionism itself, but because many Provisionists come from Baptist theology

The important nuance is this:

Arminianism and eternal security usually do not go together.
Provisionism can go either way, but in practice often goes with OSAS.

If you want, I can give you a tighter 3-line comparison of Calvinist / Arminian / Provisionist on perseverance, apostasy, and assurance.