らしい

1. 1Apparently / it seems: a conclusion based on hearsay or on evidence the speaker has gathered, stated without claiming certainty.Ex. 1
2. 2I hear: passing on secondhand information about someone else's plans or situation, often casually with よ.Ex. 2
3. 3Typical of / befitting: noun + らしい describes something that shows the characteristic qualities of that noun, as in 彼らしい.

Common in everyday conversation and also usable in neutral writing. In its inferential sense it signals that the statement rests on outside information, such as a forecast, a rumor or what others said, or on clues the speaker has noticed, so the speaker keeps some distance from the claim. Compared with ようだ, it leans more toward hearsay and less toward the speaker's own sensory judgment.

• ようだN4「ようだ」 leans on the speaker's own observation and impressions, with a softer tone, while 「らしい」 relies more on external information such as hearsay; 「ようだ」 can also pair with 「まるで」 to express metaphor. Attach 「の」 after nouns and 「な」 after な-adjectives before 「ようだ」.
• そうだN4「そうだ」 attaches to plain forms to express hearsay, only relaying information without conjecture (the appearance pattern is 「降りそうだ」); it takes 「だ」 after nouns and な-adjectives, and does not itself change into past or negative forms. In relaying information the two are close in meaning, but 「らしい」 usually carries a tone of conjecture.
• みたいだN4「みたいだ」, when expressing conjecture, focuses on what the speaker has seen or experienced firsthand and is strongly colloquial; it can also express metaphor, 'like ~' (「夢みたいな話」), and inflects like a な-adjective (「みたいな」「みたいに」).
• とみえる / とみえてN3「とみえる」 only expresses inference based on signs, not hearsay, and leans toward written language; it takes 「だ」 after nouns and な-adjectives, as in 「留守だとみえる」; it can also use 「とみえて」 to link to a following clause, which states the fact serving as the basis.
• に違いないN3「に違いない」 only expresses conjecture, and specifically the speaker's strong conviction that something 'must be' the case; when conjecturing, 「らしい」 avoids making a firm assertion and keeps its distance, and can also express hearsay and the sense of 'typical of' something. The difference in tone is large, so they should not be swapped.

ようだ and its casual form みたいだ mainly express the speaker's own judgment from direct observation, whereas らしい leans more on hearsay or outside information. Hearsay そうだ simply relays a report and appearance そうだ (stem + そうだ) describes how something looks, while とみえる is a more literary inference from visible evidence and に違いない shows strong conviction rather than reported information.