Pension presentation, GAAP vs IFRS

Understand that pensions can appear better in regards to funded status under IFRS rules than GAAP. But what specifically makes their appearance seem more positive if they’re actually underfunded, unrealized G/L, and how is reconciliation with GAAP done for comparrison? Thanks

They appear better funded because there are losses which are ‘off balance sheet’. If the Co has Actuarial gains, then IFRS will appear worse.