The taekwondo of the 1960s was more or less utterly indistinguishable from Shotokan karate, because taekwondo is best-understood historically as a Korean lineage of Shotokan with only minor and gradually-realized influences from native martial traditions like subak or taekkyon. Shotokan is the only martial art which all of its founding figures had in common and the source of the vast majority of its pedagogical style, technical repertoire and training practices.

For instance, see Hyun-Bae Kim's An Investigation into the History of the Taekwondo Uniform since the Korean Peninsula’s Liberation from Japan for a discussion of how the training uniform used by students of the early schools or kwans that later unified under the International and World Taekwondo Federations was fundamentally identical to the karategi, with Koreanizing touches like a black collar and trim or the abandonment of the fold-over style of the garment in favor of the more hanbok-like pull-over style of the modern dobok having to wait until 1978 in every case but that of the Mudokwan.

The history of the name of the art, too, is instructive: the very term 'taekwondo' wasn't coined until 1955, with most of the kwans using some variation on 'Tang Soo Do' until unifying- which is simply the Korean reading of the Japanese characters that read 'kara-te', translating in both cases to 'Tang [Dynasty] Hand/Fist'.

Technically, it's a an art taught while wearing gis, with chambered punches, a colored belt system with ten junior and ten senior ranks, versions of the Pinan, Naihanchi, Ba/Passai, and Jitte kata, sweeping forearm blocks, and a fundamentally similar technical syllabus to karate. It looks like a duck, walks like a duck, quacks like a duck, is descended from Anas zonorhyncha and insists on being called an 오리 rather than a duck largely for political rather than taxonomic reasons.