jeungsangi biseushaedo sarammada hoebokhaneun siganeun dareudae.

-아/어도 means even if, even though, or although.

So:

• 비슷하다 = to be similar
• 비슷해도 = even if it is similar / even though it is similar

In this sentence, it sets up a contrast:

• the symptoms may be similar,
• but the recovery time can still be different.

So 증상이 비슷해도 means something like even if the symptoms are similar.

Here, 증상이 uses the subject marker 이/가 because 증상 is the subject of 비슷하다 in the first clause.

So the structure is:

• 증상이 비슷해도 = even if the symptoms are similar

Using 이/가 is natural when you are simply identifying what is similar.

If you used 증상은, it would sound more like as for the symptoms..., which gives a different topic/contrast feeling. That is possible in some contexts, but 증상이 is the more straightforward choice here.

-마다 means each, every, or from one ... to another, depending on context.

So:

• 사람 = person
• 사람마다 = for each person / from person to person

In this sentence, it means the recovery time varies depending on the person.

A very common pattern is:

• 사람마다 다르다 = to be different from person to person

So 사람마다 is not the subject by itself here; it works more like by person or depending on the person.

This is a very common Korean grammar pattern: a verb can directly modify a noun.

• 회복하다 = to recover
• 회복하는 = recovering / that recovers
• 회복하는 시간 = the time for recovering / the time it takes to recover

In natural English, this is usually translated as:

• recovery time
• the time it takes to recover

So 회복하는 is a noun-modifying form of the verb.

This is similar to patterns like:

• 먹는 음식 = food that one eats
• 자는 시간 = sleeping time / time for sleeping
• 공부하는 학생 = a student who studies

Korean often uses this kind of verb + noun structure where English might prefer a noun phrase.

Yes, 회복 시간 is also possible.

The difference is mainly in style and nuance:

• 회복 시간 = recovery time
  
  • shorter
  • more compact
  • more noun-like
• 회복하는 시간 = the time it takes to recover
  
  • slightly more descriptive
  • emphasizes the action/process of recovering

Both are understandable, but 회복하는 시간 sounds a little more explanatory.

은/는 marks the topic and often adds contrast.

Here, 시간은 highlights recovery time as the thing being contrasted:

• Even if the symptoms are similar,
• the recovery time, however, is different from person to person.

So 은 helps create the contrast between:

• 증상이 비슷해도 = even if the symptoms are similar
• 회복하는 시간은 다르대 = the recovery time is different, they say

If you used 시간이, the sentence would still be grammatically possible, but 시간은 fits the contrast much better.

다르대 is a casual contracted form of 다르다고 해.

It means something like:

• they say it’s different
• I heard it’s different
• apparently it’s different

So this is not just a plain statement of fact. It has a reported speech / hearsay feeling.

Compare:

• 달라요 = it is different
• 다릅니다 = it is different
• 다르대 = they say it is different / I heard it is different

So 다르대 suggests the speaker is passing along information rather than just directly stating it.

Yes, 다르대 is casual and conversational.

More polite versions would be:

• 증상이 비슷해도 사람마다 회복하는 시간은 다르대요.
• 증상이 비슷해도 사람마다 회복하는 시간은 다르다고 해요.

If you want to make it a direct statement instead of reported speech, you could say:

• 증상이 비슷해도 사람마다 회복하는 시간은 달라요.

So the choice depends on whether you want:

• reported information → 다르대요 / 다르다고 해요
• direct statement → 달라요

A good way to parse it is in chunks:

• 증상이 비슷해도 = even if the symptoms are similar
• 사람마다 = from person to person
• 회복하는 시간은 = as for the time it takes to recover
• 다르대 = it’s different, they say

So Korean builds the sentence step by step until the final verb.

This is a useful reading strategy: instead of trying to convert word-for-word immediately, group it into meaningful parts first.