I would say that it isnt accurate to lump them with the KKK. The KKK itself wasnt a group that is "Anti-Blacks kill them all" but rather a group vested in ensuring blacks (im referring to them as this since pretty much all the texts ive read do) were economically and socially subservient via brutal physical attacks on the blacks themselves and whites who spoke out.

In terms of lynching they would be considered part of a posse rather than crowds in that they hunt down specific blacks and brutally kill them but do not like crowds, parade and take pictures and make the whole thing out to be a joyous occasion. Rather relying on the killings to send a message to the community.

Black Panthers on the other hand did not specifically target whites they deemed to be anti-black since this would be counter-productive. What in fact they did do was organize armed blacks to defend blacks against police aggression. The ones that did kill whites were not officially sanctioned but rather the "bad apples" of the group.

Im going to insert this here as a sort of context paragraph. The KKK was concentrated primarily in the South while the Black Panthers (BP) was concentrated in the North. The main difference between the South and the North was the way blacks were oppressed in that in the North it was primarily legal violence via the way of the police, while the South was extra-legal violence. This means that in the North the police would conduct raids, strip searches etc on the blacks while cruising with shotguns in arms around black neighborhoods. In contrast the South had militant white groups of which the KKK was a part of which targeted outspoken whites or blacks with extreme violence to ensure the blacks wouldnt speak or protest. In the North the police violence made it possible to use ones knowledge of constitutional rights to resist, while in the South constitution doesnt matter when some guy doesnt care about the law and is going to shoot you anyway.

This difference meant that the BP was possible in the North while being impossible in the South since in the North they had different tools available i.e. firearms which in the South would have resulted in punitive punishment. Its partly why the non-violence approach of Martin Luthor King and other groups was so successful compared to other movements at the time.

That is not to say however there were no armed black groups during this period of time in the South since many non-violent protests had armed protesters protecting them during the early 1960s (they sort of faded out over time).

Part of their hate group image comes from various measures by Federal forces particularly the FBI where COINTERPOL targeted BP specifically (236 of 250 operations were conducted against the BP). However this came about primarily in the words of the leader due to the violent revolutionary words spoken by various prominent party members at the time.

What is forgotten is that the BP also did other things during this time that didnt involve armed revolution. Things such as carry firearms in public and telling black men/women who were being targeted by policemen of their rights under the constitution (i.e. the right to remain silent), which had the effect of suppressing the policemen who sought to abuse their power against blacks. They also organised meetings to inform blacks of their constitutional rights while also organizing black voting parties that went to enrol to vote. Other measures involved lending bail money to prisoners, lending money to people who needed it and sending speakers across the country to educated and organize blacks nationwide.

The BP also differed in that they offered things such as the breakfast initiative that offered free breakfast to children who couldnt afford it, organizing the food, carpools, cooks etc for these children. They also set up medical centers where blacks could receive free treatment from volunteers.

Over time however the Federal targeting made things very difficult for them economically (paying constant bail hurts the bank) so they migrated away from a militant stance to a more pacifist one which they also deemed more effective with the passing of various laws which denied a few of their strategies (i.e. the hidden gun law that didnt allow the carrying of weapons in public which was targeted at the BP).

So TL;DR the KKK is a militant white hate group, the BP is much much more complex than that.

What ive posted so far is very very very very brief and it barely covers the differences between the groups but ill leave a few readings for you to check out.

The Revolution Will Not Be Televised Community Activism and the Black Panther Party, 1966-1971

Black radicalism and political repression in Baltimore the case of the Black Panther Party

Civil Rights Activism in 1960s Virginia - doesnt directly pertain to the BP but talks about armed protesters vs non-violent protesters

They Finally Found Out that We Really Are Men’ Violence, Non‐Violence and Black Manhood in the Civil Rights Era - same as above

Describing and Accounting for the Trends in US Protest Policing, 1960−1995 - Non-violent protests more likely to be met peacefully and not broken up

The Black Panther Party and the long civil rights era