CREATE TABLE table_201_25 (id DECIMAL, "party" TEXT, "leader" TEXT, "from" TEXT, "to" TEXT)

compare the scottish national party to the conservative and determine which party had their leaders in office for a longer time .
SELECT "party" FROM table_201_25 WHERE "party" IN ('scottish national party', 'conservative') GROUP BY "party" ORDER BY SUM("to" - "from") DESC LIMIT 1
SELECT "party" FROM "table_201_25" WHERE "party" IN ('scottish national party', 'conservative') GROUP BY "party" ORDER BY SUM("to" - "from") DESC NULLS LAST LIMIT 1