Both political parties were in their infancy during the Gladstone/Disraeli era of British politics (with the Tories being slightly older), but what were their (as opposed to specifically Gladstone and Disraeli's) core ideologies and where did their views actually differ and to what extent?
The Victorian Liberal Party's beliefs can be summed up in the slogan "peace, retrenchment and reform":
"Peace": They were internationalist, seeking to resolve disputes peacefully e.g. Gladstone submitted the Alabama claims to arbitration and during the Eastern Crisis opposed supporting the Ottomans because they were massacring Bulgarian Christians. What was later called an "ethical foreign policy" was what the Liberals wanted, viewing international relation in moral terms rather than the balance of power. They also believed in reducing armaments. Britain during the Victorian period had a small (by Continental standards) Army. I can't remember the historian's name but he commented on the fact that it was hard in Victorian England to come across colonels, generals, etc. compared to Germany, for example. Relying on the Royal Navy, the Liberals saw no need for a large standing army.
"Retrenchment": Government spending was viewed as welfare for the rich paid through taxing the poor and middle classes. Therefore, the Liberals wanted to reduce indirect taxation on the poor and raise money through an income tax on the more wealthy. Borrowing was viewed negatively as this would increase the national debt. Abolishing all but a few indirect taxes and having a relatively high income tax threshold meant that the working class was relatively lightly taxed.
All Liberals agreed on Free Trade. Not only for economic reasons but because they believed if all the world traded freely together, the causes of wars would cease. In this they were sincere but utopian. Government restrictions on trade was viewed as retarding natural economic developments as well as iniquitous, as protection was viewed as protecting wealthy landowners and businessmen at the expense of the poor who relied on cheap, imported food.
"Reform": The Liberals were in favour of increasing the number of men who could vote, though universal suffrage was supported by only a fringe. Reform also meant abolishing abuses such as being able to purchase a commission in the Army. The ideal was for an honest, transparent, equitable government.
The Conservatives were forced to accept the repeal of the Corn Laws by the 1850s. In their hearts a considerable number of Conservatives would have favoured retaining protection but it was not politically feasible as it was a vote loser.
Conservatives were more in favour than the Liberals in promoting Britain's interests abroad. Disraeli's support for the Ottomans was based on preventing Russian expansion into the Mediterranean, which was viewed as threatening Britain's connection to India. Salisbury also ensured Britain's continued naval dominance by embarking on rearmament and also added territories in Africa to the British Empire.
Social reform in this era was piecemeal, usually having broad support. Salisbury passed an Act in 1885 ensuring better housing for the working class, clearing some slums. Various Factory Acts were passed to limit working hours. The most prominent supporter of these was a Tory peer, Lord Shaftesbury (the "poor man's earl"). But the Gladstonian structure remained. Disraeli's ideas of "Young England" from his youth were not implemented during his later life as Prime Minister. Although there were some soundings about a New Social Alliance between the workers and the aristocracy against the middle class Liberals, this did not take off. Although apparently the capitalist class always distrusted Disraeli as their enemy.
Similarities? The Conservatives did not seriously challenge the hegemony of liberal ideas on the economy after accepting the repeal of the Corn Laws. Under the Conservatives, free trade and low taxes remained. During the agricultural depression of the 1870s caused by cheap imported food, Disraeli rejected protection. They also rejected any form of conscription for the Army. The Liberals for their part did not disestablish the Church of England or abolish the House of Lords.
Sources: E. F. Biagini, Liberty, Retrenchment and Reform. Popular Liberalism in the Age of Gladstone, 1860–1880 (Cambridge: Cambridge University Press, 1992). Robert Blake, Disraeli (London: St. Martin's Press, 1967). Andrew Roberts, Salisbury: Victorian Titan (London: Phoenix, 1999).