Difference between third pillar 3A and 3B

Premise: Both pillar 3A (tax-qualified) and pillar 3B (non-tax-qualified) have the same function, that is, to accumulate capital (savings) and cover the risks of disability and death.
In fact, many companies offer the possibility to switch from 3A to 3B, without the need to change contracts.
However, the differences are substantial, let's look at the main ones.

Third pillar 3A: the premium paid can be deducted from taxable income, and when it is withdrawn at retirement, income tax will be paid (at a reduced rate).

Third pillar 3B: the premium paid is declared as a capital sum (savings capital), and when it is withdrawn, it will remain as a capital sum, so there is no income tax.

3rd Pillar 3A: Must be stipulated until the ordinary retirement age (or until the age of 70 if you intend to work beyond the age of 65)

3rd Pillar 3B: You can freely choose the duration. That is, there is no link to retirement.

Third pillar 3A: follows the same regulations as the second pillar (BVG), therefore you can withdraw funds in advance to purchase your first home, if you become self-employed, or if you leave Switzerland permanently.
Third pillar 3B: you can withdraw funds in advance, even without a specific reason.

Pillar 3A: The standard clause applies: 1st wife/husband, 2nd sons/daughters, 3rd other legal heirs

Pillar 3B: Free choice of beneficiaries, even outside the family circle. 

The answer is, as always, “it depends”.
It depends on your income and the taxes you pay.
It depends on who you need to include as a beneficiary.
And above all, it depends on the purpose for which you are doing it.
To find an answer to all these “depends”, it's best to ask for competent advice. That way, with the numbers and facts in hand, you can make the best decision.