It's hard to lookup what the answer was as of 2015, but as of 2019 the tables have turned with the Netherlands having one more visa-free country (Mongolia) than Sweden. Otherwise the two passports have similar visa-free/e-visa access rights.
The latest Henley Passport Index disagrees, as it still puts Sweden (186) above the Netherlands (185). However if we look at the underlying data, we can see the following list of "visa required" countries for the Netherlands:
Afghanistan
Algeria
Angola *
Azerbaijan *
Benin *
Bhutan
Burundi
Cameroon
Central African Republic
Chad
China
Congo (Dem. Rep.)
Congo (Rep.)
Cote d'Ivoire (Ivory Coast)
Cuba
Djibouti *
Equatorial Guinea
Eritrea
Ghana
Guinea
India *
Iraq
Liberia
Libya
Mali
Myanmar *
Nauru
Niger
Nigeria
North Korea
Oman *
Pakistan *
Russian Federation
Saudi Arabia
South Sudan
Sudan
Syria
Turkey *
Turkmenistan
Vietnam *
Yemen
And the following list for Sweden:
Afghanistan Algeria Angola * Azerbaijan * Benin * Bhutan Burundi
Cameroon Central African Republic Chad China Congo (Dem. Rep.) Congo
(Rep.) Cote d'Ivoire (Ivory Coast) Cuba Djibouti * Equatorial Guinea
Eritrea Ghana Guinea India * Iraq Liberia Libya Mali Mongolia Myanmar
* Nauru Niger Nigeria North Korea Oman * Pakistan * Russian Federation Saudi Arabia South Sudan Sudan Syria Turkmenistan Yemen
(the * symbol signifies countries that issue e-visas to the above-mentioned passport holders)
The differences are thus:
- Mongolia is visa-free for the Netherlands, as mentioned above
- Turkey issues e-visas to Dutch citizens, but is visa-free for Swedes
- Vietnam has the same policy as Turkey
In practice the differences between e-visas and schemes such as ESTA are quite blurry, therefore whether or not Swedes enjoy more visa-free countries is a matter of debate :)