Generally speaking...... estate passes the capital gains thru to beneficiaries, who include them on their personal return.

Taxation--- If sell on contract, have the option of taking income into tax return on installment basis.....reportable in the year cash is received, and under the tax laws in effect at time of each receipt.  If take all money in lump sum, the gains are reported as of that point.

Economically speaking........selling on contract also means that a seller could get the benefits/detriments of buyer defaulting.

No tax benefits/detriments to buyer whether buy on installment contract or lumpsum.