Why did NSDAP hate communism (socialism), despite having socialism within the party?

This is a part of the very general pattern: your worst enemies are those whose views are close you your own, rather than those whose views differ radically. Examples:

For the early Christians, the worst animosity was between various Christian sects (which differed very little) rather than between Christians and Pagans,

For the Catholic church the worst enemies were Muslims and Jews (fellow monotheists), protestants, heretics.

For Stalinists: Trotskyists and other "deviationists", rather than "capitalists".

For the Nazis: fellow socialists.

Why did Germany during the era of NSDAP have a different point of view on socialism?

In short: it was the difference between:

Nationalism is an ideology that strives for identification and solidarity among all members of a nation and wants to unite the latter in a sovereign state.

and

Internationalism refers to ideas or efforts that go beyond the framework of the nation state or that consider a transnational level to be decisive or worth striving for.

Nationalsozialismus – Wikipedia
Bezeichnungen
„Nationaler Sozialismus“ bezeichnete im deutschsprachigen Raum seit etwa 1860 Verbindungen von nationalistischen und sozialistischen Ideen. Vom „Nationalsozialismus“ sprach zuerst die 1903 in Österreich gegründete Deutsche Arbeiterpartei, die sich 1918 in Deutsche Nationalsozialistische Arbeiterpartei (DNSAP) umbenannte. Entsprechend benannte sich auch die 1919 in Deutschland gegründete Deutsche Arbeiterpartei (DAP) 1920 in NSDAP um.

Mit der Bezeichnung „Nationalsozialismus“ grenzten diese neuen Parteien ihre Ideologie gegen den Internationalismus der sozialdemokratischen und kommunistischen Parteien und vom konservativen Nationalismus älterer Parteien ab, indem sie sich deren Wählerschichten (Arbeitern und Mittelstand) als bessere Alternative anboten. Außerdem stellten sie einzelne antikapitalistische Forderungen in den Rahmen eines völkisch-rassistischen Nationalismus und präsentierten sich seit 1920 als „Bewegung“, nicht als Partei, um so Protestwähler und Politikverdrossene zu erreichen.

Designations
"National Socialism" has been used in German-speaking countries since around 1860 to describe the combination of nationalist and socialist ideas. The German Workers' Party, which was founded in Austria in 1903 and renamed itself the German National Socialist Workers' Party (DNSAP) in 1918, first spoke of "National Socialism". Accordingly, the German Workers' Party (DAP), founded in Germany in 1919, renamed itself NSDAP in 1920.

With the term “National Socialism”, these new parties differentiated their ideology from the internationalism of the social democratic and communist parties and from the conservative nationalism of older parties, offering their constituency (working class and middle class) a better alternative. In addition, they placed individual anti-capitalist demands within the framework of a folkish-racist nationalism and presented themselves as a “movement” from 1920, not as a party, in order to reach protest voters and those disenchanted with politics.

Sources:

• Nationalsozialismus – Wikipedia (in German)
• Internationalism (politics) - Wikipedia
• Nationalism - Wikipedia

NSDAP have a different point of view on socialism?

It didn't really. The "socialism" in the party's name was never anything more than a great big steaming pile of marketing. They were always a far-right Nationalist Populist party. The hallmark of nationalism being a desire to have all of their own culture under the same state (and little to none of anybody else's), and the hallmark of populism being an ideology that the common people are being controlled and thwarted by a nefarious elite.

Political science had not yet really fully studied populism, so it was not really a term in common use until the 1950's (although many similar right-wing parties did use "People's Party"). So the original name of the party was just "The German Workers Party".

The "Workers" in there was a nod to the fact that in a democracy they needed some kind of appeal to to the working class in order to have any hope of getting a serious amount of votes. The only pro-worker program they really espoused was getting rid of the Jews and socialists and other assorted undesirables and traitors who were supposedly secretly controlling the government (again: this is what we today consider classic populism).

The "socialist" was inserted into the name in 1920, over Hitler's objections, and again purely as a marketing ploy. The party was positioned as a racist far-right anti-Marxist party both before and after the name change.

In general, the manifesto was antisemitic, anti-capitalist, anti-democratic, anti-Marxist and anti-liberal. To increase its appeal to larger segments of the population, on the same day as Hitler's Hofbräuhaus speech on 24 February 1920, the DAP changed its name to the Nationalsozialistische Deutsche Arbeiterpartei ("National Socialist German Workers' Party", or Nazi Party). The word "Socialist" was added by the party's executive committee (at the suggestion of Rudolf Jung), over Hitler's initial objections, in order to help appeal to left-wing workers.