How does the SDLP differ from Sinn Féin in terms of nationalism?

Question

Both parties are described as (Irish) nationalist by Wikipedia. After losing all Westminster seats in 2017, the SDLP made a comeback this December, gaining back two seats.

Speaking of seats, unlike Sinn Féin, SDLP seems to take their seats at Westminster; in fact the current SDLP leader even criticized Sinn Féin for not doing so. Also, Financial Times recently described the SDLP as "moderate nationalists". But how does the SDLP nationalist position otherwise differ from that of Sinn Féin when it comes to the path they see for Irish reunification?

Answer 1

Historically the SDLP was committed to peace while Sinn Fein was the political wing of the Provisional IRA terrorists.

John Hume (SDLP leader and Nobel Peace prize laureate) was instrumental to bringing peace to Northern Ireland.

Martin McGuiness (leading Sinn Fein politician) was an admited IRA member, convicted for involvement in bomb-making, and deemed by the Republic of Ireland goverment to have been a member of the PIRA "Army Council" (ruling body). The Savill enquiry concluded that during Bloody Sunday he had been actively taking part in paramilitary activities and was likely armed with a Thompson submachine that he may have fired (though not in a way that would justify solder's firing). Gerry Adams was also considered by the RoI government to be on the Army Council though the evidence is less strong.

Those two did help in ending PIRA terrorism and I suppose benefit from the joy over sinners repented.

Guardian - Ministers accuse Adams of IRA Role

John Hume not Sinn Fein steered NI peace process

Savill Inquiry - Events of the Day

Re taking seats in Westminster, it is fundamental to Sinn Fein's ideology that the UK government has no legitimacy in Ireland and to take their seats would be to acknowledge that. They will not compromise on it.

The SDLP believe in democratic process within the UK constitution, especially now that the RoI has removed the clause from its constitution asserting sovereignty over the North.

Answer 2

In more recent times, i.e. since January 2019, the SDLP has created formal cross-border ties with Fianna Fáil, which interestingly seem to cover a common vision on Irish unity.

Fianna Fáil has promised a couple of years ago to publish a 12-point plan on their vision of Irish unity, but as of this summer, the plan was (still) not finalized or at least not published. But one aspect on which they disagree with Sinn Féin is holding a border poll right after Brexit happens.

Answer 3

The policy of abstentionism, of not taking seats at Westminster, has deep roots in Irish history, going back to the 19th century, long before Adams and McGuinness and the violence of 1969-98.

Sinn Féin was founded in 1905 and ran abstentionist candidates as long ago as 1908. Sinn Féin candidates elected in the 1918 UK general election formed Dáil Éireann, the first legislature of what is now the Irish republic.

Without going into the complexities of 20th century Irish history, it's fair to say that for most of that century Sinn Féin had close links to the IRA.

I think it's also fair to say that today, Sinn Féin sees itself as committed to peace, and as the keeper of that original, far older, absentionist tradition.

Sinn Féin's brand of nationalism is more (how can I say this?) assertive than the SDLP's, for example pushing for a border poll as noted above. Sinn Féin would also be regarded as more left-wing, and more populist, than the SDLP.