Interesting, I can see how it would sound the same, with a different accent.

Native English speaker. I tried saying both out loud and it sounds the same. It's just a glottal stop (?) either way in my accent.

"Hard c" is voiced, "g" is unvoiced.

(I think you mean the other way around.)

But the difference is almost meaningless in this case because in practice the c blends to the d, which is voiced.

They should sound different. Not a lot different, but there is normally a noticeable difference between g and c sounds.

It matters what the tongue and voice box are doing in the surrounding sounds. The next letter (t) is voiced, and the prior sound is a vowel, so in practice many English speakers will continue to “voice” the c sound between e and d, the “g” is just a voiced “c”, which makes them homonyms in most speakers.

(This post brought to you by YouTube, who keep putting Dr Geoff Lindsey in my recommendation queue, and now I’ve become a part time linguistics enthusiast. Other interesting facts: “chr” and “tr” are also almost entirely homonyms in most speakers. Try saying “trooper” and “chrooper” and see what I mean. In fact my 4 year old, who is recently learning to write, drew a picture of a truck and wrote “chruck” on the paper.)

Plus all of the differences between native speakers.

Canuck here. Color and colour are pronounced differently(mildly), and ant and aunt wildly different. Suite and suit are different pronunciations too.

Yet to some US speakers, those words are the same.