יְהוּדָה (H3063) yᵊhûḏâ

Ιουδα (G2448) iouda

Ἰούδας (G2455) ioudas

Mark 6 (ASV):3

Is not this the carpenter, the son of Mary/am and brother of “Jacob/us” and Joses/p/h and Judas and Sim(e)on? And are not his sisters here with us?” And they took offense at him.

Matthew 10:4 Simon the Zealot, and Ἰούδας Iscariot, who betrayed him.

• Ἰούδας (Ioudas, G2455) Judah Genesis 35 This is the direct transliteration of the Hebrew name יְהוּדָה (Yehudah) into Greek. It is used in the New Testament for multiple people, most famously Judas Iscariot, but also Judas the brother of James, Judas Barsabbas, and others.
• Ἰουδαία / Ἰουδαῖος / Ἰούδα (Iouda, G2448) Genesis 29 This form is basically the same name, but the endings shift depending on whether it refers to the tribe/territory (Judah/Judea) or the patriarch Judah. Grammatically, Ἰούδα (without the final -ς) is often the genitive or accusative form, or sometimes just a slightly different spelling tradition when referring to the Old Testament figure Judah rather than New Testament persons named Judas.

The difference is largely in Greek case endings and usage.

• Ἰούδας (with -ς) → nominative masculine singular, used for persons in the NT (e.g. Judas Iscariot).
• Ἰούδα (without -ς) → genitive/accusative forms, or a conventional spelling when referring back to the OT patriarch or tribe of Judah.

the Hebrew name יְהוּדָה (Yehudah) was transliterated into Greek as Ἰούδας (Ioudas), regardless of whether the referent was:

• the OT patriarch (Judah , son of Jacob),
• the tribe/kingdom (Judah, Judahites)
• an individual in the NT (Judas Iscariot, Judas Barsabbas, Judas the brother of Jesus, etc.).