ISA vs Pension Explained

You have money to invest each month and two boxes it could go in, both wrapped in jargon. Give the amount, your situation and tax band. You get the practical difference between a Stocks and Shares ISA and a personal pension: access rules, tax going in and coming out, the employer match angle, then which to prioritise for you.

I have {MONTHLY_AMOUNT} to invest and I am not sure whether to put it in an ISA or a pension. My situation: {PERSONAL_SITUATION}. My tax band: {TAX_BAND}.

Explain the practical difference between a Stocks and Shares ISA and a personal pension in plain English. Focus on the access rules, the tax treatment going in and coming out, and the employer contribution angle. Then tell me which I should prioritise given my situation, and whether the answer changes at different income levels.