There’s no simple answer, but the key difference between a Lifetime ISA and pension is tax. You receive tax relief on pension contributions at your highest marginal rate (currently 20%, 40%, or 45%), whereas you don’t on contributions to a Lifetime ISA, although as long as you continue to qualify, the Government will add a cash bonus to your Lifetime ISA of up to £1,000 per year on top. Since your Lifetime ISA is made up of money you’ve already paid income tax on, you’ll be able to make withdrawals tax free. A pension works the other way: tax relief now, pay tax when you draw it down.
Generally, higher rate taxpayers see larger tax relief over the lifetime of a pension than when withdrawing from a Lifetime ISA.
Contribution limits on pensions are also generally significantly higher than with a Lifetime ISA, which are restricted to £4,000 per annum.